363 



animals which were exposed. Most of the other fourteen gave signs 

 of having suffered from the exposure before they were killed. Some 

 became insensitive to tactile stimulus. Others showed alternate 

 swellings and contractions along the body. One animal turned 

 markedly browner than any of the others, although otherwise it looked 

 normal. There was some evidence of a darkening of other exposed 

 animals, which was confirmed by a microscopic study of the body wall. 

 The effort was made to fix the worms after degeneration was apparent 

 in their tissues, but before death. That this was difficult to do, is 

 indicated by the fact that half of the animals killed showed no internal 

 injury, although they did show already some of the external indica- 

 tions which have been mentioned. A comparison of the periods 

 necessary to produce death of the animals of different ages, as repre- 

 sented in the three subdivisions of the table, shows that the young 

 animals succumb much more quickly than the adult. This may be 

 due either to the greater sensitiveness of the tissues of the young, or 

 to a simple physical condition, namely that, since the diameter of 



