14 



chroaie-silver method to the selachian cerebellun. His paper 

 records observeitions with a considerable degree of detail. 

 Reference to the results of Schaper will be made niore particu- 

 larly under Section V. 



Inspired by the elaborate classification of nerve-cells 

 in general proaiulgated by Nissl in his writings, Szczawinska 

 ( '9B) was impelled to make a study of the internal structure 

 of the selachian nerve-cell. His work presents the results of 

 his researches upon certain types of cells through the use of 

 methylen-blue, safranin, and haematojiylin stains. The cells 

 studied were from the sensory ganglia, motor cells from the 

 cord and oblongata, and cells of Purkinje from the cerebellum. 

 Szczawinska reached the conclusion that the nerve-cells of 

 selachians have remained on a low plane of development. In 



support of this view he cites certain of his results (1) that 



the cell-bodies are usually bi-polar in form; {?) that there is 

 but slight demarcation between the cell-body and its protoplas- 

 mic processes; and (3) that the chromophile substance is less 

 differentiated than in teleosts and hif^her vertebrates. 



