366 G. HAROLD DREW 



with a loopful of the fluid from each tube on sloped fish broth 

 peptone gelatin, made with sea water, and the pieces of the ovary 

 were implanted into the muscle in the ordinary way. It was 

 found, considering only those cases which the cultures showed to 

 be sterile, that about the same proportion of the animals survived 

 as in check experiments, but whether the degeneration had 

 occurred in blood or in sea water, in no case was there any pro- 

 duction of ciliated epithelium. 



Experiments in which the ova were removed from the ovary and 

 then injected were unsuccessful. If the ova be shaken out into 

 sterile sea water, centrifugalised, or allowed to settle, and then 

 injected with a hypodermic syringe, it was found that a large 

 proportion of the animals died within a week, and in those that 

 survived it was impossible to find the ova on dissection. To ob- 

 viate this difficulty the centrifugalised ova were placed in a ster- 

 ilised solution of gelatin in sea water, at a temperature just 

 above the point of solidification, this was allowed to cool, and 

 portions of the jelly implanted into the muscle: unfortunately 

 this always resulted in the rapid death of the animal, presumably 

 because the gelatin has some toxic action. Agar jelly could not 

 be used for this purpose because it solidifies at too high a temper- 

 ature, and also is not dissolved by the body fluids of Pecten. 



A number of experiments were performed to prove that the 

 development of the lining layer of ciliated epithelium of the cysts 

 was not produced merely as a result of irritation, and as a reaction 

 to the implantation of any foreign body. In a previous paper 

 (Drew and De Morgan '10) the result of the implantation of the tis- 

 sue forming the gills and digestive gland of Pecten, and of sterile 

 Agar jelly, has been studied. In addition to these, such substances 

 as sterilised cotton wool, cork, elder pith, and small portions of 

 sterilised silicious sponges were implanted to act as a source of 

 irritation. In all these cases the formation of a cyst wall com- 

 posed of fibrous tissue took place, but there was no development 

 of ciliated epithelium, and the same holds good for cases where 

 the organ of Bojanus of Pecten maximus was implanted into 

 other animals of the same species. 



The transplantation of the ovarian tissue of animals of different 



