184 'journal of Comparative Neurology and Psychology. 



which are differentiated by osmic acid and the basic stains. 

 Schneider ('02) designates them in mollusca as Nissl bodies, 

 thereby implying their similarity to the well known Nissl bodies 

 of vertebrate nerve cells. In their distribution in the nerve cell, 

 they are arranged usually in concentric rows around the nucleus, 

 becoming fewer as the cell wall is approached. That such regu- 

 larly disposed bodies exist in many invertebrate nerve cells there 

 can be no doubt, but there is considerable doubt as to their dis- 

 tribution even in the same family; and as to their significance we 

 possess no generally accepted conclusions. 



Closely associated with these regular-shaped and regularly 

 distributed Nissl bodies are some bodies to which the term mito- 

 chondrien and chondromiten (Rhode, '04 a) is given. Rhode 

 would include here also the Nissl bodies. The term chondro- 

 miten is used when there is a considerable accumulation of a 

 densely-staining substance in the cytoplasm. The collection of 

 several bodies (mitochondrien) gives rise to a mass which is known 

 as chondromiten and conversely the chondromiten may break up 

 into a number of small bodies known as mitochondrien. Rhode 

 makes a great deal of these various combinations m which he tries 

 to establish a genetic continuity. The result is that he advances 

 a hypothesis of elementary organisms for the cell which is a modi- 

 fication of Altmann's bioplastic hypothesis. 



In general it may be said that Holmgren and his followers look 

 on these structures as the expression of an activity in the cell and 

 that under different physiological conditions the cytoplasm 

 reveals different structural states. 



After spending considerable time on the cytology of nerve cells 

 in mollusca, I became convinced that, unless the cause of these 

 remarkable structures could be resolved, not only was all theoriz- 

 ing futile, but also a correct interpretation of the facts as well. In 

 the further work which is now well under way on this and kindred 

 topics Dr. C. G. Rogers will be associated with me and it is our 

 purpose to follow careful physiological experiments by cytological 

 observations. 



Haminea sohtaria. — Concerning the question as to whether the 

 lymph spaces have a definite wall other than would be formed by 

 the granules of cytoplasm, I do not wish at this time to make any 

 statements for or against the contentions of Holmgren, Rhode 

 and Bergen. 



