2l8 C. M. CHILD AND L. H. HYMAN. 



his conc'usion concerning either the action of cyanides on oxi- 

 dation in Paramecium, or the results of the susceptibility method. 

 In papers soon to be published we shall show that KNC produces 

 a very marked decrease in both oxygen consumption and carbon 

 dioxide production in Planaria. 



His conclusions concerning oxygen consumption and suscep- 

 tibility during starvation indicate that he has failed to take into 

 account a second important fact, viz., that metabolic conditions 

 in ectoplasm and entoplasm may be different and may change 

 more or less independently. As a matter of fact Lund's data on 

 starvation metabolism in Paramecium, as far as they go, are in 

 full agreement with, though much less complete than, the results 

 of our own studies made during the last two years on starvation 

 metabolism in Planaria, but not yet published. While extended 

 discussion and criticism along this line are postponed until pub- 

 lication of our own results, it may be noted here that the appar- 

 ent discrepancy between susceptibility and metabolism appears 

 in Planaria as well as in Paramecium, but as regards Planatia, 

 it has been possible to demonstrate that it is only apparent. In 

 well fed animals the metabolism in the alimentary tract is a very 

 large part of the total, and during the early stages of starvation 

 this metabolism at first decreases very rapidly as the alimentary 

 tract becomes less and less active functionally. During this 

 period, however, the functional activity and metabolism of the 

 surface and body wall continue and the susceptibility method 

 shows that the susceptibility of the body wall remains unchanged 

 or increases slightly, but it also shows that the susceptibility of 

 the alimentary tract as compared with that of the body wall 

 decreases to a very marked degree. In other words, if we take 

 into account the susceptibility of the alimentary tract as well as 

 that of the body wall, which the data published in earlier papers 

 did not do (Child, '14*2, '156, Chap. VII.), the discrepancy be- 

 tween the results on susceptibility and those on metabolism dis- 

 appears. 



In the more advanced stages of starvation, concerning which 

 Lund presents no data, perhaps because Paramecium, being a 

 single cell, dies before it reaches such stages, when all food and 

 all reserves are gone, and the animal is living upon its own proto- 



