438 



of 1 : 200 after twenty-four hours they were macerated so that the 

 different systems of muscle fibres could be recognized. 



Oligochaeta. Earthworms, probably small specimens of L. ter- 

 restris, were washed in water and then transferred to solutions of dif- 

 ferent strengths. In the stronger solutions they become motionless 

 after from one to five minutes and at the same time greatly relaxed 

 and elongated. After from ten to twenty minutes they were put into 

 alcohol (35°/ ) when they began slowly to contract. The contraction 

 is most active in the posterior region and stops by the time or before 

 the worm has reached its normal length. By this method the anterior 

 fourth of the worm is preserved in a very well extended condition — 

 quite equal or perhaps superior to the best specimens obtained by 

 slow alcoholic narcotization. For the study of the anatomy of the worm 

 this method can be recommended. In the weaker solutions (l : 1000 

 and 1 : 1500) the worms retained their power to move and remained 

 alive for days. 



Ro tiferà. This method was tried especially with Lacmularia 

 socialis (probably an allied species). In the stronger solutions the ani- 

 mals were neatly relaxed and eventually came out of their cases. In 

 weaker solutions they were fairly well expanded. 



Mollusca. Young fresh- water snails are made more transparent 

 than in their normal state. They as well as older individuals in solu- 

 tions from 1 : 300 to 1 : 1000 eventually fall out of the shell in a fully 

 relaxed condition, with the tentacles in some cases nearly twice their 

 normal length. In strong solutions Anodons open their shells in a 

 few hours. By this method fine specimens may be obtained and the 

 labour of preserving them lessened. 



Crustacea. Daphnia, Ostracods and Copepods become more than 

 normally transparent in Chloretone solutions of from 1:200 to 1 : 1000. 

 In Daphnia all the parts are relaxed, the heartbeats normally and there 

 are feeble movements of the appendages, sufficient only to show their 

 position. In 1 : 200 after twenty -four hours the body hangs out 

 ventrally from the shell bringing the appendages into full view. The 

 effect upon Ostracods resembles that on Daphnia. Copepods, however, 

 are more resistant. 



Tadpoles. In solutions of all strengths movement ceases in a 

 few seconds. In strong solutions the heart stops beating. In solutions 

 of from l:1000tol:2000 almost any degree of anaesthesia can be 

 produced depending upon the time of immersion, and the animal can 

 be brought again to a normal condition. The tail can be operated upon 

 without causing a return of consciousness ; and when the tadpole is 

 put into water again its actions subsequently appears to be normal. 



