52 'Journal of Comparative Neurology and Psychology. 



The great dilations of the canals are certainly only accidental, and so one can 

 understand without anything further the great variability of the canals. 



After working upon a variety of animal forms both vertebrate and invertebrate, 

 and especially upon Lophius, the author concludes that his former position in 

 harmony with that of Fritsch ('86) is a mistaken one and that the vessels are not 

 blood vessels within the nerve cells but are to be considered as lymphatic in their 

 nature, and that they press their way into the nerve cells and there branch about. 

 Among the invertebrates he finds Astacus and Palaemon, next to Lophius, excellent 

 material for clearing up the true nature of the lymph canals. 



In very young animals he finds the canal net to be remarkably simpler than in 

 the case of older animals. Often this net is to be found at one pole of the very 

 eccentric nucleus. The sympathetic nerve cells of the mammals show the canal 

 nets only within the cell body. The same nerve cells of the bird, like the central 

 nerve cells of all the vertebrates studied, possess continuations of the net also within 

 the dendrites. An electrically stimulated nerve cell of the bird will show, according 

 to Holmgren, the presence of the lymph canals in the neurites. 



Fig. 2. The intracapsular cells surround the nerve cell. The trophospongium branches as a net of 

 coarse threads through the endoplasm and at two points reaches the surface connecting itself with the 

 colored bodies of the intracapsular cells. After Hoi mgrex ('04, Fig. i). 



The question as to the morphological and genetic character of the lymph canals 

 has been much discussed and various opinions held. Nelis considered them as 

 achromatic hyaline bands, but he seemsto be somewhat uncertain in his meaning. To 

 him they are riddles as to morphology and function. Holmgren and his followers 

 believe them to be canal-like, fluid carrying structures. According to Holmgren 

 and his followers the bands of Nelis are only modified parts of the lymph-canals. 

 Holmgren opposes the view that they are formed out of the nerve cells but holds 

 that they press into the substance of the nerve cells from without in the form of 

 hollow processes (Kapselfortsatse). He further claims to have seen unmistakable 

 nuclei-bearing capsule processes in the spinal nerve cells of Lophius and other 

 teleosts, also in the gastric ganghon cells of the Crustacea, within which there were 

 sap spaces. According to his view these canals do not represent drainage tubes 

 but are rather the morphological expression of certain phases of the penetration of 

 nerve cells and the intracapsular cells belonging to them. The trophospongium 

 has pseudopodia-like mobility whose intensity is supposed to depend upon intra- 

 cellular chemical processes (Fig. 2). 



The lymph-canals are of a lymphatic nature and are certainly associated with 



