February 2, 1952 NATURE 197 of the Cells Within the First Few Ho=S to About the Its Life-History As a Parasite in Diopatra

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No. 4292 February 2, 1952 NATURE 197 of the cells within the first few ho=s to about the its life-history as a parasite in Diopatra. The observa same extent as the prototroph yield is increased, the tions reported here confirm Dr. Brown's suspicions. multiplication being supported by growth factors The significance of these observations lies in the present in the supernatant liquid and presumably fact that very few cases of parasitism have ever been derived from the full medium on which the parent described among the polychaites and rarely, if ever, strains were cultured. has a polychrete been described which parasitizes On the other hand, the experiments with the Hfr another polychaite. Dr. Ralph Smith• has reviewed strain, while supporting the former conclusion, also a case which was described by Koch in 184 7 as an give some indication that the high frequency of example of viviparity in Marphysa. Certain later recombination in crosses involving the Hfr strain is workers considered this to be a case of a parasitic not to be accounted for in the same way as the lumbrinereid. It may be noted that Marphysa, behavio= of the supernatant liquids. Lumbrinereis, Diopatra and Arabella are all members More details and further results will be published of the same family, the Eunicid::e. later. Just how the stages of Arabella here reported get One of us (G. A. M.) was supported during this into the tube-dwelling Diopatra is, as yet, an un work by a scholarship from the British Council ; the solved problem. other (C. P. B.) by a scholarship from Newnham l\L JEAN ALLEN College, Cambridge. Department of Zoology, G. A. MACCACARO University of New Hampshire, CYNTHIA p. BOOTH Durham, Department of Genetics, and the Marine Biological Laboratory, Whittingehame Lodge, Woods Hole, 44 Storey's Way, Massachusetts. Cambridge. Sept. I. Aug. 14. 'Fanvel, P., "Polych~tes Errantes" (Faune de France, 5), 1 (1923). 'Lederberg, J., Genetics, 32, 505 (1947). 'Smith, Ralph I., J. Morph., 87, 417 (1950). ' For the composition of media and the meaning of symbols, see Lederberg, J ., ref. 1. ' Cavalli, L. L., 100th meeting of the Genetical Society (Cambridge, 1949). Hunger-Reaction of Flies (Musca) and the Functions of their Stomatogastric System An Example of Parasitism among DURING my work with house flies (Musca domestica Polychcl!tes L.) I noticed one day that the bodyless heads of I HAVE observed a case in which the young of about ten flies all made drinking movements when one polychmte annelid, Arabella-probably A. iricolor their tongues came in contact with sugar water, but, (Montagu), the cosmopolitan species which is common probably due to quick desiccation of the cesophagus, to the Woods Hole area-parasitizes another poly no sugar water ever passed through this passage. chmte, namely, Diopa,tra cuprea (Bose.). On August After some time, the sucking movements became 24, I recovered fifty-three complete worms of the more vigorous and then rather suddenly stopped. genus Arabella, and the parts of approximately ten In the case of flies with their tongues forcibly in others from one adult Diopatra. The segment from touch with sugar water, the pumping activity of the which the parasites were recovered was approxim fulcrum, even when the crop was full, never ceased. ately one and a half inches in length. '!.'he Arabella Only the contra pressure from the crop prevented ranged in size from small worms of approximately a further intake. These experiments suggest that the thirty segments without eyes or setai to large worms sucking reaction takes place independently of the with four eyoR (arranged in the transverse row typical hunger- or thirst-condition of the fly. for the genus) and with numerous segments (up to Allowing a fly to walk over a sheet of filter paper approximately 180), some of which contained setai. sprinkled with sugar water, it was found that a The largest parasite was approximately 5 cm. in length, starved fly will stop as soon as one of its front tarsi as compared with the adult Arabella, which ranged comes in contact with a moistened spot, stretch out 1 in size from 50 cm. to 60 cm. in length • The larger its tongue and try to drink. parasitic Arabella appeared to lie free in the ccelom, In a number of starved flies the crop was ligatured. whereas the smaller ones were held in place by the Two of these flies showed hunger-reaction after the small parietal blood vessels in the body-wall of operation. In four cases when the crop was removed Diopatra. after a small meal, the flies' hunger-reaction remained. On August 27, a second infected Diopatra was The reverse experiment, in which the crop was re observed. This animal and the other infected worm moved from three flies after they had been allowed came from the same batch, which was dug at Hadley to eat as much as they desired, showed that none Harbor, Nonamesset Island, near Woods Hole, of them behaved as if it was hungry. Flies without Massachusetts. Most of the Arabella recovered from a crop eat often and little at a time, but otherwise the second infected animal were small. Twenty-six they behave normally. Seven flies had the abdomen complete worms and parts of approximately four removed after a big meal. Not until an hour or two others were obtained. Most of these small parasites later did their thirst- and hunger-reactions return, had no eyes, no setai, and relatively few segments, and then their reactions to sugar water and distilled a number having as few as seven segments. water increased rapidly. The flies were able to detect Several years ago, during the first part of August, a droplet of water near them by means of their Dr. Frank Brown observed three or four large Arabella antennm, and then if their front tarsi were simult emerging from the body cavity of Diopatra (personal aneously brought into contact with droplets of sugar communication). He suspected, at that time, that water and pure water, they turned towards the sugar Arabella may normally go through certain stages of water. From these experiments it may be concluded