The Method of Making Models from Sheets of Blotting Paper
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THE METHOD OF MAKING MODELS FROM SI-IEETS OF BLOTTING PAPER. BY SUSANNA PHELPS GAGE. Ithaca, New York. The Born Method of reconstructing models from wax plates is in use in all the larger laboratories of Anatomy and Embryology. Various modifications of that method have been introduced, notably at Johns IIopkins University. For smaller laboratories and isolated investigators the wax plates are difficult to prepare or to obtain already made. More- over, in the larger laboratories ihe preparation of the plates is a much dreaded piece of drudgery to be done in the basement. The apparatus is cumbersome and if at all accurate, expensive. Like any other ap- paratus it requires some skill to use it with success. Any one who has either cast or rolled wax plates will not need a statement of the inconveniences. In 1905, it occurred to me that sheets of blotting paper might serve instead of wax plates. A small model was at once made which showed its feasibility. Models made of this material were demonstrated at thc Association of American Anatomists in December, 1905, ( Amer. Jour. Anat. V., 1905-06, p. XXIII) and the method was further demonstrated at the International Zoological Congress held in Boston, August, 1907'. It has also been used successfully in the embryologic and anatomic laboratories of Cornell University and the University of West Virginia. Blotting paper models were demonstrated by Dr. J. H. Hathaway and by Dr. J. B. Johnston at the Association of American Anatomists held in New York, 1906 (Proc. Assoc. Amer. Anatomists, Anat. Record, April 1, 1907,). Usually with the Born method the wax plates are 1, 2, or 3 mm. in thickness and the sections of the specimen are lop or some other multiple of 5, thus making the magnification at which the drawing of the sec- tions should be made, a simple problem in proportion. It has been objected that it is difficult to obtain blotting paper of a given thickness. This is indeed true. In Ithaca, at a wholesale paper dealer's one package was bought in which the paper was of the desirable Nov. 10, '07. The Anatomical Record 167 thickness of one millimeter. The thickness since obtainable is 0.5 nim., 0.77 mm. and 0.9 mm. The following steps give a general outline of the method used: 1. For testing the thickness, a pile of 40 pieces of the same size cut from diffe'rent sheets of the blotting paper is held closely together by a rubber band. One end of the block so formed is dipped in hot paraffin and compressed with the fingers. The measurement of the parafflned end divided by the number of pieces gives the working thickness of the paper. 2. Size of model and thickness of plates.-Suppose a model is to be made of a specimen cut into a lop series and the blotting paper avail- able has a thickness of 0.9 mm. or 9OOp. Each sheet is 9OOp divided by lop = 90 times as thick as the sections. The simplest case would be for a model 90 times as large as the object. Then each section is drawn at a magnification of 90 and a plate of the blotting paper is used for each section. Suppose it were desirable to use a magnification of 120. Each section is drawn of the proper size, and must be represented by a thickness on the model of 120 X lop = 1200p or 1.2 mm. One plate is 0.9 mm. thick, that is 0.3 mm. less than it should be. In every three plates there is a loss of 0.9 mm., a loss which is made good by using two sheets of blotting paper for every third section, that is, for every group of three sections four pieces of blotting paper would be used. Suppose a magnification of 60 were desired, then each section if drawn at a magnification of 60 should be represented on the model by 60 X lop = 600p or 0.6 mm. As the thickness of the paper is 0.9 mm., one plate is 0.3 mm. too thick and three plates would be 0.9 mm. too thick. Hence if every third plate is omitted the correct thickness is secured. In practice the drawing of every third section is omitted. Other problems are easily met as occasion demands by adding plates or omitting the drawing of certain sections. The slight inaccuracy thus produced is negligible. 3. Thickness of paper, size of model and magnification having been determined, the drawings of sections are made upon the blotting paper by the aid of a camera lucida, or more satisfactorily with a projection microscope. One or more duplicate drawings may be easily secured by using carbon paper and thin sheets over the blotting paper. 4. The difficulty of cutting wax plates is considerable. This difficulty has been met by Dr. E. TJ. Mark by using a sewing-machine with an electrically heated wire as cutting edge. (Demonstrated at the Asso- 168 The Anatomical Record Now. 10, ’07. ciation of American Anatomists, December, 1906. Method published in the American Read. Arts and Sciences, March, 1907. See also Science, XXV, 1907, Anat. Record, Apr., 1907.) With the blotting paper, if the drawings are small the cutting is easily done with scissors or a knife. When the drawings are large and especially when the model is to be made by representing each section by two to four thicknesses of blotting paper it has been found that an ordinary sewing-machine can be used to do the cutting. By setting the regulator for the shortest stitch an almost continuous cut is made and the parts are easily separated. If a large sewing-machine needle is sharpened in the form of a chisel, the cut becomes considerably smoother. It has heen found advantageous when long continued or heavy work is to be done to attach to the machine an electric sewing-machine motor. Skill in guiding the work is soon acquired. Therc are some details of a complicated drawing which are more easily cut by the scissors or a knife after the main lines have been cut by the machine. 5. It is a great advantage in any working model to have sections at regular intervals in marked contrast with the body of the material. Blot- ting paper of a large variety of colors (black, red, blue, pink) is easilg obtained in the market. In the models made every tenth plate was a bright or light color and every lOOdth was black, rendering rapid num- eration easy. 6. \Then the paper sections are thus prepared they are piled and re- piled as is usual until the shape conforms to an outline predetermined from photographs, drawings, or iueasurements made before the specimen was cut. It has been found that an easily prepared support and guide for the model in process of setting up, is made by cutting the outline to be fol- lowed from a block of four or five sheets of blotting paper, marking upon it the lines of direction for every tenth or twentieth section. The colored numerating plates must of course conform to the spacing and direction of these lines. ‘7. The preliminary shaping having been accomplished more exact modeling is undertaken. The paper sections slide very easily upon one another. The most satisfactory means of fastening them together is by the use of ribbon pins, ordinary pins, or wire nails of various sizes, depending upon the size of the model. No kind of paste or glue was found suitable for this purpose. 8. When the model is well formed, inequalities are best removed by rubbing with the edge of a dull knifc and smoothing with sand paper. Nov. 10, ’07. The Anatomical Record 169 Any dissections of the model for showing internal structures should be planned for at this stage for it is now more easily separated than later. It is also at this time that superfluous “bridges,” which have been left in place to support detached parts, would better be removed. 9. To finish the model it is held together firmly and coated with hot paraffin either by a camel’s hair brush or by dipping in paraffin and removing the superfluous coating by a hot instrument. On a very large model Dr. Hathaway used a thermo-cautery for this purpose. The paraffin renders the model almost of the toughness of wood with- out destroying the lightness of the paper. 10. For coloring the surface of the model, it was found most desirable to use Japanese bibulous paper (the lens paper of the microscope deal- ers) which had been dipped in water color and clried. Any of the laboratory dyes or inks can be used, such as eosin, picric acid, methylene green, black ink, etc. The colored lens paper molds over the surface with ease and is held in place by painting with hot paraffin. All color and enumeration lines and fine modeling show through the transparent paper. When the model ceases to be a working model it can be covered with oil paints mixed with hot paraffin and rubbed to any degree of finish desired. 11. One can dissect the model by a hot knife run along the planes of cleavage or cut across them by a saw. The advantages claimed for blotting paper models arc the ease and cleanliness of their production and the lightness and durability of the product. The models are broken with difficulty, are easily packed or transported, and when they cleave apart are easily repaired, thus contrast- with the weight and fragility of wax models and their deformation by heat.