FUNDULUS AND THE SURROUNDING MEDIUM. 12$ 



others when transferred from sea water to fresh water, and since 

 an increase in weight occurs when they are thus treated, the idea 

 occurred to me as to whether the change in weight is less for the 

 surviving individuals than in the case of those dying. Accord- 

 ingly a number of experiments were tried with individuals trans- 

 ferred to separate dishes each containing a liter of fresh water. 

 Each specimen was rinsed in fresh water, the free water absorbed 

 on a soft clean towel, the specimen weighed and then placed in 

 the dish indicated above. After a certain period the specimen 

 was again similarly weighed and replaced in the dish with fresh 

 water again. As a check a number of specimens were rew^eighed 

 immediately. The dish in which they were weighed was also 

 weighed after the fish was removed and compared with its former 

 weight. No fish w r as handled more than was absolutely neces- 

 sary. In fact handling was limited to picking the fish from the 

 towel, placing it in the experimental dish. 



Difference of opinion exists as to the effect of removing the 

 scales or injuring the skin. For example, Bert found that the 

 removal of mucus from the skin of the eel caused its death in 

 sea water where it would otherwise survive this transfer. He 

 found that the eel survived transfer from fresh to salt water 

 and was surprised when in a similar experiment carried out by his 

 assistant, the eel died. He learned that the assistant had un- 

 consciously removed mucus from the skin of the eel in the 

 struggles involved in making the transfer. The experiments of 

 Garrey corroborated Bert. Removing the scales or skin from 

 portions of the surface of the body resulted in the rapid death of 

 Fundulus heteroclitus on being transferred to fresh water, or to 

 sea water, but of those kept in diluted sea water, approximately 

 isotonic with the blood, none had died at the time the others 

 were dead. Sumner obtained opposite results for in an experi- 

 ment which he carried out at Woods Hole; he transferred Fundu- 

 lus heteroclitus to sea water full strength or to diluted sea water 

 having a sp. gr. of i.ooi. He found that most lived although 

 the skin had been removed from one entire side of the fish. In 

 fresh water all these fish were dead in a few days. Sumner 

 called attention to the well-known fact that hardy species survive 

 mutilations of the body surface. In fact in experiments which 



