An Antique Microscope Slide Brings the Thrill of Discovery Into a Contemporary Biology Classroom

ARTICLE An Antique Microscope Slide Brings the Thrill of Discovery into a Contemporary Biology Classroom

Frank reiser

AbstrAct that few others share my interests), I add them to my growing collection. The discovery of a Victorian-era microscope slide titled “Grouped Flower Seeds” began When I found skillfully prepared Victorian-era microscope slides listed an investigation into the scientific and historical background of the antique slide to under the category “Folk Art” in an antique dealer’s online catalog, it led develop its usefulness as a multidisciplinary tool for PowerPoint presentations usable in not only to my acquiring them but also to the beginning of a journey contemporary biology classrooms, particularly large-enrollment sections. The resultant involving Internet and library research, trips to herbaria, field collecting presentation was intended to engage students in discussing historical and contempo- excursions, and, finally, to the development of a PowerPoint lecture for rary biology education, as well as some of the intricacies of seed biology. Comparisons between the usefulness and scope of various seed identification resources, both online community college biology students. The slide that triggered the snow- and in print, were made. balling project is titled “Grouped Flower Seeds” (Figure 1). Having spent most of my life as a biology educator, I view most of Key Words: Grouped Flower Seeds; Watson and Sons; antique microscope slide; what I encounter in life from a science-oriented perspective. Finding pre- online seed identification resources; seed identification manuals; seed biology; pared microscope slides described as “folk art” sharply conflicted with large-enrollment lecture. my sense of the correct order of disciplines – particularly for items that I would reverently classify as the tools of scientists. The antique dealer’s Large-enrollment lecture sections are difficult teaching environments for case for placing antique slides under a “folk art” heading is arguably practitioners of constructivist or inquiry-based methodologies. As class correct from an artistic perspective. The most straightforward defini- sizes grow, I find that my efforts need to be logarithmically increased to tion confirming that comes from Oregon State University’s Department overcome the “alone in a crowd” feeling seemingly of Anthropology, which defines folk art as “any wedded to budget-saving, mass-education modes. art created by a self-taught individual” (http:// Thankfully, the digital projector has become ubiq- I am fascinated by old oregonstate.edu/instruct/anth370/). This defini- uitously available for educators who desire to tion encompasses microscope slides of subjects connect intellectually with the individual student science equipment, such as micro-writing (example: The Pledge of awash in a sea of heads. When one couples the particularly pieces related Allegiance written on a grain of rice) within the projection device with digital photography and a purview of the arts and provides good fodder for display program such as PowerPoint, a computer- to biology teaching. student discussions as to where the line should savvy educator can compile and express the per- be drawn. sonal experiences of learning and discovery to large groups. For me, a fulfilling part of teaching is being able to share with a class J The Who, What, Where & When what I am currently studying and the pathways that I’ve had to follow – pathways that usually intersect other disciplines, such as history, culture, of the Slide art, business, and more. Every disciplinary intersection provides an oppor- William Watson & Sons, Company, London (1834–1957), was a large tunity for students viewing the presentation to link what they have previ- supplier of optical instruments and prepared microscope slides, selling ously learned to the biological content of the day’s curricular goals. by catalog in both England and the United States between 1834 and 1957. Why would a company produce and market a microscope slide of J The Teacher’s Interest Triggers flower seeds glued in a symmetrical arrangement? There are no indica- tions that “Grouped Flower Seeds” (GFS) was intended to serve a pur- the Process pose in academic biological study. Simply put, the GFS slide was made to I am fascinated by old science equipment, particularly pieces related to be an entertaining novelty for the thriving amateur microscopist market biology teaching. When items are affordable, which is often (so I suspect of the time. From 1837 to 1901, which many biologists have dubbed

The American Biology Teacher, Vol. 74, no. 5, pages 311–317. issn 0002-7685, electronic issn 1938-4211. ©2012 by national association of biology Teachers. all rights reserved. request permission to photocopy or reproduce article content at the university of california press’s rights and permissions Web site at www.ucpressjournals.com/reprintinfo.asp. doi: 10.1525/abt.2012.74.5.5

The american biology Teacher anTique microscope slide 311 Figure 1. “Grouped Flower Seeds,” a prepared microscope slide arrangement of 92 angiosperm seeds glued on an opaque background. Produced by W. Watson & Sons, High St., London, ca. 1890 (10×).

the “Golden Age of Natural History,” nature study was a popular pas- time. Having a microscope in the home was not uncommon among families well-off enough to have leisure time. Exploring nature’s microscopic world was a hobby enjoyed by many microscope owners, while others less involved might set up a microscope with slides as a conversation seed-crystal during social functions. Figure 2. After 1907, “Ltd.” was added to the Watson label; “Grouped Flower Seeds” is a dry mount with an opaque black its absence indicates that the GFS slide was produced earlier. background, requiring oblique, top-stage illumination for microscopic Notice the glass slide’s finished edges and corners and the viewing. Ninety-two small seeds are glued into a geometric pattern, black enamel ring sealing the specimen. surrounded by a metal collar to prevent the cover slip from touching the seed arrangement. Outside the mount, gloss enamel paint seals the chamber from external humidity. There is no mounting medium filling spectacles and magnifying glasses into producing microscopes and cam- the space between the seeds and the cover slip, so the slide is fragile. eras of the firm’s own design. Their catalog advertised a large microscope Rough handling could dislodge the seeds from their positions, ruining slide inventory until World War II (1939), at which time the company GFS’s geometric arrangement, so allowing students unsupervised viewing was conscripted to manufacture optical instruments for military use. of the deep-mount slide would be risky. After the war ended, the company, now owned by the founder’s grand- The slide’s date of creation is estimated to be between 1890 and children, dropped prepared slides from the company catalog. A few years 1907. The approximation was inferred by comparing the labels affixed later they retired, permanently closing the company’s doors. to GFS with matching label designs used by W. Watson & Sons, as By avocation, William Watson was a horticulturalist and maintained illustrated in Bracegirdle’s compendium of antique microscope slides his own greenhouse. He conducted experimental crosses between flower (Figure 2). Additionally, a Watson & Sons advertisement listed a slide varieties, publishing a number of his studies in respected journals of the titled “Grouped Flower Seeds” in the 1893 edition of Hardwicke’s Science time. How involved Watson was in the production of the GFS slide is not Gossip, confirming the existence of a slide with the same name being known, but he unquestionably had access to a variety of plant seeds for offered by the company during the corresponding time range. Because the slide’s production – an important consideration when searching for Watson & Sons resold slides made by other commercial preparers under the identity of the seeds used to make the slide (Bracegirdle, 1998). their label, the actual creator of GFS is not known; but with databases I purchased the GFS slide for several reasons, not the least of which containing digitized catalogs, magazines, newspapers, and books of the was the opportunity to add an interesting piece to my personal collection period rapidly growing online, the GFS artisan may yet be uncovered. of Victorian scientific paraphernalia. I also wanted to incorporate the William Watson started his business as an optician’s shop in London, slide’s image into my class lectures, using it as an interdisciplinary bridge England, in 1837. By 1876, the company had grown from manufacturing between biological, historical, and artistic arenas. Another reason for

312 The american biology Teacher Volume 74, no. 5, may 2012 Figure 4. An aril of Nemesia (GFS seed 7). The lacy disseminule Figure 3. “Grouped Flower Seeds” identification key. with a striated border is an outgrowth of where the seed (1) Silene latifolia alba. (2) Oxalis stricta. (3) Portulaca pilosa. attaches to the parent plant’s ovary wall (funiculus). Nemesia’s (4) Cinquefoil. (5) Senecio vulgaris. (6) Campanula. (7) Nemesia aril aids the wind dispersal of the true seed hidden inside the sp. (8) Orobanche (?). (9) Antirrhinum sp. (10) Digitalis purpurea. delicate cage. (11) Nasturtium officinale or Petunia sp. (12) Gentiana. purchasing GFS was that owning the slide would allow me to display the The mea culpa that I make while lecturing about the GFS slide to a item for student examination whenever I believe it would be beneficial class is a confession of my intentional use of the vernacular definition of to do so. I always fear that there is a credibility gap between projected seed. I first make clear what botanically is truly a seed and then explain PowerPoint images and the “real thing” in students’ minds. The physical the less precise, more commonly understood meaning for the term and presence of GFS in the classroom helps bridge the divide between the why disseminule is a better word choice. Nevertheless, after that admis- PowerPoint images and the real thing. I allow students to view the slide sion, all of the disseminules/diaspores in the arrangement (whether aril, by setting up a hands-off demonstration stereoscope for viewing during achene, or true seed) are collectively called “seeds.” The botanical termi- the lecture break. (Transparent tape holds the slide to the stage.) But to nology used in this paper is in accordance with that used in the seminal effectively use GFS in a biology course, I needed to identify the seeds in work on seed dispersal by Leendert van der Pijl (1969; a digitized ver- the arrangement (Figure 3). sion is currently available at http://onlinelibrary.wiley.com/doi/10.1002/ fedr.19710810814/abstract). J A Botany Educator’s Mea Culpa Botanists know well that, when teaching about seeds, not everything J Seed Identification Keys Are the Rarae referred to as a “seed” is precisely that. To be botanically correct, the term seed should be limited to the reproductive unit that contains the embryo Aves of Biological Manuals of the plant-to-be, along with its stored food and encapsulating seed Working to identify unknown seeds is a daunting task. Seed taxonomists coat or test. Often, seeds are embellished with additional parts, derived use a complex vocabulary that can quickly dishearten the uninitiated, from the floral remnants of the parent plant that serve to aid the “true dashing expectations that an unknown seed’s identity could be uncov- seed” in its protection and/or dispersal (Figures 3 and 4). But even the ered with an easy look-up. Increasing the task’s tedium is the fact that botanically cognizant casually refer to both true seeds and “seeds with most authoritative seed descriptions are scattered throughout botanical accessories” simply as “seeds.” Because practitioners in the sciences need publications over a wide time span. precision when speaking or writing formally, the botanical term of choice Searching Bowker’s Books in Print for currently available seed iden- for both true seeds as well as those carrying extra parts is disseminule, a tification guides returns only one: Seed Identification Manual (Martin & catchall term that covers all variations of reproductive packages, botani- Barkley, 2000). The guide is a reprint of the 1961 edition published by cally known by terms such as aril, achene, capsule, caryopsis, nut, drupe, the Regents of the University of California, which lists Alexander Camp- and true seed (Figure 4). Sometimes an entire plant is considered a dis- bell Martin as the sole author – a name familiar to anyone who collected seminule, as in the case of tumbleweeds. Propagule and diaspore are two the Golden Guide paperback nature series popular during the 1950s. The other terms for botanical procreative packages. Diaspore was introduced guide is profusely illustrated with black-and-white photographs of 600 in 1927 by Sernander as a term restricted to angiosperm reproductive species of seeds, but, unfortunately, the reissued version of the book has units (Booth, 1988). Propagule is a term with more “wiggle room,” as reproduced the pictures with a quality lower than that of the original edi- its definition includes both sexual and asexual methods of reproduc- tion. Also unfortunately, the book does not include a key, so identification, even extending to a horticulturist’s leaf and stem cuttings. Biology tion requires a lot of page-flipping to match up the unknown seed with teachers often find themselves torn between using germane terminology the images. Thanks to used-book dealers listing their stock online, the and courting their students’ understanding. first edition is findable (with patience).

The american biology Teacher anTique microscope slide 313 There are four other out-of-print seed identification guides that can usually be obtained with little difficulty. The Illustrated Taxonomy Manual of Weed Seeds (Delorit, 1970) covers 192 species with a dichotomous key to aid in searching, and Weed Seeds of the Great Plains: A Handbook for Identification (Davis, 1993) covers 280 species with a polychotomous key. Both books contain excellent color photographs. The U.S. Department of Agriculture’s (USDA) 1963 agricultural handbook, Identification of Crop and Weed Seeds, covers 623 species with black-and-white photographs referenced by working through a “drill down” series of technical keys. The handbook is agriculturally oriented and resultantly provides the best Graminae (grass family) seed coverage of all the references. Once one begins seeking to identify an unknown seed, the importance of having as many references as possible is quickly realized.

J Online Seed Identification Databases Figure 5. Silene (GFS seed 1). The jigsaw pattern of interlock- The two most extensive seed-identification guides available online are ing cell walls making up the seed coat is an identifying char- the USDA’s Family Guide to Fruits and Seeds (FGFS; available at http:// acteristic of the pink family. Digital databases allow “skipping nt.ars-grin.gov/sbmlweb/OnlineResources/frsdfam/) and Colorado State ahead” in the identification process with a single characteristic University’s SeedImages.com (CSU-SI; available at http://www.seed such as this. images.com/). At the time of this writing, a $30-per-semester subscrip- tion is required to access the CSU-SI database. Both the FGFS (3216 images) and CSU-SI (1700 images) websites with a useful teaching tool? I doubt that many would find it to be so. The provide tutorials for using their databases, and both have search pro- original slide is a historical artifact that brings with it an aura of reality grams that provide a clickable list of “legal” seed descriptors used in each connecting viewers in the 21st-century classroom with their counter- of the databases – a helpful feature in a field fraught with synonyms. parts during the Golden Age of Natural History. Real things carry with Searching the CSU-SI database will return a list of seed pictures with them a hard-to-describe, but nevertheless engaging, quality that is mean- descriptors that match the searched-for term, as well as all other descrip- ingful to many – as seen by museum attendance outperforming that of tors linked to that picture. This is a very different process than working movie theaters (Katz, 2010). through a printed dichotomous key, where the researcher cannot con- Although the GFS slide was produced and distributed for 20 years, it tinue if the information needed to respond to a morphological question is rarely found for sale today. Luckily, antique microscope slides covering set is unknown. Skipping ahead in a taxonomically based dichotomous a wide range of topics are gaining in collectible status. Many now get at key obliterates the tool’s purpose and value, even though jumping ahead least one listing cycle on online auction sites where they stand a chance and working a key in reverse can be instructive. By contrast, computer of rescue before being discarded. The applicability of an antique slide’s searches of online seed databases are nonlinear and remain workable contents to contemporary biology curricula is a call only the educator with just a few descriptors. When using the CSU-SI database, each can make. In my case, when I first saw the slide, something inside me seed picture displays the entire list of “legal” descriptors for the seed. whispered, “Come, Watson, come! The game is afoot.” Comparing the picture with its associated terms serves as a vocabulary-building process, enabling the researcher to refine the next search J Field-Gathered Information about attempt (Figure 5). In the FGFS database, the seed’s descriptors are linked to the taxo- Three Seeds from the GFS PowerPoint nomic plant families, so the search returns a list of all the seeds in that Presentation plant family in the online database. Sifting through such a large number of pictures to identify a seed is time-consuming but is in keeping with White Campion Silene latifolia (= Silene alba) the key’s stated objective of being a “Guide to Plant Families.” White campion, seed number 1 in the GFS arrangement, is a dioecious, The gold standard for seed taxonomists is the physical matching of short-lived, perennial herb native to Eurasia, and now an invasive weed the unknown seed with known specimens in a seed herbarium collec- found over most of North America (Figure 6). As with many invasive tion. The FGFS has been created by photographing examples held by the plants, white campion quickly colonizes disturbed soils, which occa- U.S. National Seed Herbarium (BARC) at the U.S. National Arboretum, sionally might be a newly dug grave. For this reason, along with its habit Washington, D.C., which, at 120,000 seed taxa, is one of the largest in of nocturnal blooming, in England the plant has been dubbed “the grave the world. Researchers can make arrangements with the BARC to have flower.” White campion’s seeds are held within capsules formed by the specimens drawn from the collection for close-up examination. ovary wall (Figure 7). When mature, the seed capsule splits open at its apical end (partial dehiscence), with tooth-like cusps curving outward J Folk Art Set the Stage but Biology as it dries. The urn-like vessel, now surrounded by 10 teeth, two for each of the flower’s carpels, will sprinkle out its reproductive contents Education Stole the Show only when the stem is vigorously moved about by the wind or a passing Would contemporary reproductions of the GFS slide, this time accompa- animal – a dispersal process called “the saltshaker method,” or anemob- nied by an identification key and guidebook, provide biology educators allism. White campion was classified as Lychnis alba until the 1960s, but

314 The american biology Teacher Volume 74, no. 5, may 2012 Figure 7. Silene latifolia’s maturing capsule cut longitudinally to reveal developing seeds attached to a central placenta. Two mature seeds have detached and can be seen on the lower right.

Figure 6. Silene latifolia’s five filamentous stigmas extend above the flower’s corolla, identifying the sex of the entire plant as female. The mature seed-filled capsule has split open at its apical end. because other members of the Lychnis genus split their seed capsules to form five teeth and white campion makes 10, it was moved into the toothier genus Silene. Recent genetic barcoding data strongly suggest that species within the pink family have been taxonomically “oversplit,” and a “reclumping” may lie in the plant family’s future (Mayol & Rosselló, 1999).

Woodland Groundsel Senecio sylvaticus Woodland groundsel, seed number 5 in the GFS arrangement, is an annual plant of wastelands and poor soils, unlike the almost identical common groundsel (S. vulgaris), which is a nuisance species of richer, cultivated lands (Figure 8). Groundsels are self-fertilizing plants that produce parachute-adorned achenes that carry seeds considerable distances by wind. Botanically, this is termed anemocherous seed dispersal. Should the hairy crown become wet at the time of its opening, the hydroscopic pappus cannot spread apart the thistle-filaments needed to increase the disseminule’s aerodynamic profile. Damp seeds will not travel far from home (Figure 9). A pappus’s attachment to its achene is weak, a fea- Figure 8. Senecio sylvaticus is also known as “old man of the ture allowing for easy separation between the two units. As any para- woods” because of the gray-haired appearance created by chutist knows, being dragged about on the ground by a wind-driven hundreds of fluffy pappi attached to the seeds (Latin pappus = chute makes getting a foothold difficult. It is for this reason that seedless “old man”).

The american biology Teacher anTique microscope slide 315 pappi blowing about in the wind are often seen. After the achene loses its pappus, a circular collar remains on the disseminule’s apical end, an important identifying feature visible on the seeds used in the GFS arrangement.

Yellow Woodsorrel Oxalis stricta Yellow woodsorrel, seed number 2 in the GFS arrangement, is a her- baceous plant bearing small yellow flowers and clover-like compound leaves (Figure 10). The prolific little plant can plague greenhouse owners and landscapers because it thrives in cramped spaces such as flowerpots, gaps between bricks, and cracks in sidewalks. Yellow woodsorrel is easily grown in classrooms year-round, either near windows or under artificial lights, producing seedpods irrespective of the season (Keefe, 1965). This allows pods to be readily available for demonstrating the plant’s ballistic seed-dispersal method to students whenever needed (Figure 11). When growing plants on my office windowsill, I was surprised to find the tiny (0.9 mm) seeds sticking to the window’s smooth glass, as well as to the ceiling more than 6 feet away. While manipulating the plants, I have been shot in the eye with a seed more than once. Students working with

Figure 9. An achene of Senecio sylvaticus with its thistle-like pappus attached.

Figure 11. A misfired Oxalis seed hooked on hair adorning Figure 10. Oxalis stricta blossom and a developing seed pod the parent plant’s pod. The vertically split (dehiscence) pod still surrounded by five calyces. holds the spent, crumpled, white aril between its lips.

316 The american biology Teacher Volume 74, no. 5, may 2012 Leaver, M., Dominguez-Cuevas, P., Coxhead, J.M., Daniel, R.A. & Errington, DNA in GFAJ-1 does in fact contain arsenicDanilov, in placeR.A. & ofEkelund, phosphorus, N.G.A. (2001). Using the green flagellate Euglena J Conclusion J. (2009). Life without a wall or division machine in Bacillus subtilis. but a number of other researchers are not readygracilis to Klebs accept as thisphysiological report. dosimeter: is a long-term bioassay Nature, 457, 849–853. Most students display considerableHowever, enthusiasm Wolfe-Simon’s when designing team has already publishedmore significant a second than apaper short-term one? Turkish Journal of Botany, and conducting their experiments onin ScienceEuglena, ,the frequently journal thatchoosing published the first25, 43–44. one (Pennisi, 2011). Mlot, C. (2009). Antibiotics in nature: beyond biological warfare. 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(1991). are picky. Manual about of Vascular their homes Plants on of humanNortheastern skin. analysis. They draw on their prior knowledgenorm. And of it’s cell risky and evenpopulation putting it in thisWashington, column because D.C.: National by the Academy Press.United Science States, 320 and, 1001. Adjacent Canada. new york, ny: new york botanical garden. J biology and discover new knowledgetime Acknowledgmentsfor you themselves read it, the through whole theirissue may veryRobbins, well W.J., be Hervey,settled, A. one & Stebbins, way M.E.Katz, (1950).Pennisi, p.m Studies. (2010). E. (2009). s onervice TheEuglena despite bug and stress: the bacterium:museum attendance interdependent and funding genomes. in a year experiments and literature searches.or They another. perform I can’t repeated wait. calcu- vitamin B . Bulletin of the Torrey BotanicalofScience Club recession., 77, 324, 423–441. Washington,, 1253. d.c.: american association of museums. available Black, P.J. & Wiliam, D. 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Forensic Weed identificationSeeds of the Great using Plains: skin Abacterial Handbook communities. for Identification. c Mommunityanhattan college College; and an has M.S., served also in as biology, president from of The Boston empire College; state andassociation a Ph.D. nickel and cadmium using motility and photosynthetic parameters KWIATKOWSKI ([email protected]) is a Science Laboratory Preparator lawrence, Proceedings Ks: ofuniversity the National press Academy of Kansas. of Sciences USA, 107, 6477–6481. ofin Two science year collegeeducation biologists, from N anew nabT York University.affiliate organization. Her major interests are in of Euglena gracilis. Environmental and Experimental Botany, 69, Flannery, M.C. (2011). Centering on the gut. inAmerican the Biology Biology Department Teacher ,at 73 Southern, Oregoncommunicating University, 1250science Siskiyou to the Blvd.,nonscientist and in the relationship between 68–75. 177–180. Ashland, OR 97520. biology and art.

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560 THE AMERICAN BIOLOGY TEACHER VOLUME 73, NO. 9, NOVEMBER/DECEMBER 2011 THE AMERICAN BIOLOGY TEACHER POPULATION GROWTH IN EUGLENA 473

The american biology Teacher anTique microscope slide 317

162 THE AMERICAN BIOLOGY TEACHER VOLUME 74, NO. 3, MARCH 2012