April 6, 1906.] 



SCIENCE. 



525 



made on the finer structure of invertebrate 

 nerve cells, but no one has combined to any 

 extent physiological experiments on the 

 same animal. So many terms have already 

 been proposed for the structures described 

 by other writers that no attempt is made 

 to homologize these several terms. 



In the cytoplasm of Limax and Ham- 

 inea there is present in the animal taken 

 from its normal habitat a varying number 

 of lymph spaces which exhibit neither a 

 constant shape nor a constant position. In 

 some instances the limiting wall of the 

 lymph space takes a definite stain, while 

 in others there is no indication of a struc- 

 ture which we might designate as a wall. 

 These lymph spaces in Limax are either 

 free from anj^ solid staining bodies or there 

 may be as many as a dozen different bodies 

 in a single space. To be sure that these 

 spaces and bodies were normal character- 

 istics of the cytoplasm, the nerve collar was 

 dissected from the living snail and indi- 

 vidual nerve cells studied. The spaces can 

 be seen in the unstained living nerve cell, 

 but the bodies only when some neutral 

 methylene blue is introduced under the 

 cover glass. 



The experimental evidence indicates that, 

 contrary to the usual observations on nerve 

 cells, the nucleus shows no evidence of 

 shrinkage. When Limax is stimulated 

 until exhausted by induction currents or a 

 needle the bodies which are so prominent 

 in the unfatigued animal have disappeared. 

 In order to ascertain what became of these 

 bodies the living nerve cell was mounted 

 on a slide between electrodes of platinum 

 foil and the alternating current from an 

 induction coil was then passed between the 

 electrodes. Within a half hour the dark 

 bodies began to break down; within an 

 hour or an hour and a half they had en- 

 tirely disappeared. After a period of rest 

 new bodies similar to the old ones again 

 appear in the cytoplasm. It seems to us 



highly probable that these bodies ai'e stores 

 of energy giving stuff which may be called 

 on in emergency to renew the protoplasm 

 of the cell. 



The bodies found in Planorbis seem to 

 be entirely different from those found in 

 Limax. When Planorbis is fed on chest- 

 nuts for a few weeks a large number of 

 golden-yellow bodies can be seen in the 

 unstained nerve cell accumulated chiefly 

 around the base of the axone. These bodies 

 do not stain with methylene blue nor dis- 

 appear when subjected to an electrical 

 stimulus. 



Experiments and analyses are under way 

 to determine the nature of these bodies. 



The Nematocysts of Eolis: 0. C. GL.iSER, 



University of Michigan. 



The evidence of Wright ( '58), Grosamor 

 ('04=) and myself ('04^ and later) that 

 the nematocysts in the cerata of Eolis are 

 derived from coelenterates was reviewed 

 and found valid. The adaptiveness of 

 these transferred nettling organs, however, 

 is not as easily determined as their origin. 

 Since they discharge and inflict pain, they 

 are as efficient in these respects as before 

 ingestion. My observations show, however, 

 that despite their great concentration in 

 Eolis, they are not as generally effective 

 as has been supposed. In combats with its 

 own kind, the cerata are attacked directly 

 and eaten voraciously. 



When irritated, Eolis curls up ; the 

 cerata project like quills from a porcupine, 

 or are cast off by autotomy. An attacking 

 fish is certain to fill its mouth with nemato- 

 cysts, both because the appendages contain- 

 ing them are numerous and because they 

 are most conspicuously colored. 



Various fishes behave differently in the 

 presence of Eolis. The blennie, which lives 

 in great numbers on the same hydrids with 

 Eolis, ordinarily is indifferent to the pres- 

 ence of the latter, but when aroused by 



