366 John F. Holm 



aud Sanders (41) published 1894 a («mail monograph on the nervous 

 system which gives us some histological details of the brain. 



The histology of the spinal cord has had the special attention 

 of Nansen (31) and G. Retzius (37), the neuroglia has been studied 

 by Erik Müller (30) and the question of the pineal eye by Beard 

 (4) and Studnicka (45). 



In the present work I shall confine myself to the microscopical 

 anatomy and the histology of the nervous system, as the peripherical 

 nerves and the macroscopical anatomy have already been exhaus- 

 tively treated. 



Material and Methods. 



I obtained Myxine direct from the Royal Academy of Science's 

 Biological station at Kristineberg, on the west coast of Sweden, and 

 either fixed and hardened the objects here in Stockholm, or got them 

 fixed at the station. Besides Myxine I have had one head of Bdello- 

 stoma. 



The fixing fluids used have been 



solution Bicromate 100 g 

 Commercial Formol 10 g 

 or \% Bicromate solution alone, Erlick's fluid, Kultschitzky's 

 fluid and Osmium-Bicromate solution for Golgi preparations, Zen- 

 ker's fluid and Formol Alcohol. 



The brain was either dissected out of the head or the head 

 fixed in toto after removal of unnecessary parts. 



A great number of staining methods were tried; amongst others 

 staining with Erltck's haematoxylin and Eosin in toto according to 

 His, with Para-carmine in toto and after-staining with Bleu de Lyon, 

 staining in toto with Iodide of Palladium according to Paladino, 

 section staining with the Haematoxylin method of Walters and the 

 Iron-haematoxylin method of IIeidenhain. The Golgi crom-silver 

 impregnation was used in the double and treble modification accord- 

 ing to Ramon y Cajal, either on the brain in its capsule or on 

 those where the capsule had been removed. 



The best results were obtained in the following manner; as 

 soon as the animals arrived the heads were cut off and the brains 

 removed and put into the above-mentioned Bricromate-Formol solu- 

 tion for 60 hours, nitrate of silver solution (0,7^) for the same time, 

 the ordinary Bicromate-Osmium mixture for 48 hours and finally 

 silver solution for five or six days. 



Formol-Bicromate \ ^ 



I Con 



