Eoss Granville Harrison 211 



virescens embryos into a similar dish containing a solution of the same 

 strength, the latter to be used for testing the irritability. Eight palustris and 

 two virescens embryos are placed under similar conditions in water. 



April 22. The temperature has varied between 70° and 80° F. In the 

 palustris embryos kept in water the external gills are sprouting and the 

 blood may be seen circulating in them. These embryos react reflexly to 

 mechanical stimuli; i.e., on being touched by a needle, they first contract 

 the opposite side of the body. The drugged embryos are not quite so far 

 along in their development. The heart-beat is distinct, but there is no 

 circulation as yet in the gills. There is a slight swelling in the pericardial 

 region (Fig. 12). The test embryos react locally to mechanical stimuli 

 (direct muscular stimulation). 



April 23. The temperature has been above 80° F. The embryos in the 

 acetone-chloroform solution are developing well. The circulation in the 

 external gills is good. They scarcely give even a local response to stimuli. 



April 24. The temperature has been cooler, but above 70° all day. The 

 drugged embryos are developing normally. There is no reaction to stimuli 

 except a faint local one. The solution is diluted to 0.025 per cent. 



p 



Fig. 12. Fig. 13. 



Fig. 12. Embryo of R. palustris kept two days in a 0.03 per cent solution of acetone- 

 chloroform. X 9. P = pericardium. 

 Fig. 13. Control embr5'0 kept two daj'S in water. X 9. 



April 25. Temperature this morning, 68°. The circulation is well estab- 

 lished in the tails of the palustris embryos. The virescens embroys are not 

 quite so far advanced in their development. There is no reaction to stimuli, 

 except a very feeble local one. 



April 26. Solution of drug diluted to 0.02 per cent. The circulation in 

 the tail of the virescens embryos is well established. There is only very 

 slight local reaction to stimuli. 



April 27. The control specimens kept in water are now feeding and 

 passing faeces. The drugged embryos are slightly swollen. The coils of 

 their intestines are not wholly normal. The heart action is good. Three 

 palustris and one virescens larvje are preserved. The others are put into 

 fresh water for recovery. 



4.38 P. M. Larvae put into fresh water. 



4.42. No reaction to stimuli. 



4.49. Virescens larvte react with a quiver or jerk. Palustris larv« do not 

 react at all. 



4.55. Virescens larvae are able to swim across the dish. Jaws are moving. 

 Gasping respiratory movements. Palustris larvae do not react. 



5.15. Palustris larvae do not react. 



