234 FISH. [Vol. X. 



cation to these forms of that most useful of modern neurological 

 methods : the Golgi-Cajal short silver nitrate method. Since 

 this has in so many ways revolutionized our ideas of the 

 structure of the nervous system of higher animals it seemed 

 to me more than likely that we should find in these more 

 generalized types conditions that ordinary methods have 

 hitherto failed to demonstrate. 



Technique. 



For the morphological study, sections in most cases were 

 made through the entire cranium or head, after it had been 

 decalcified. Perenyi's mixture or Gage's decalcifier was used 

 for this purpose. The latter is made up by adding 3 cc. of 

 strong nitric acid to 100 cc. of yo% alcohol, and gave uni- 

 formly good results. 



The tissue was fixed in various ways : Potassium bichromate, 

 corrosive sublimate, picric alcohol, and a mixture which may 

 be called picro-aceto-sublimate composed as follows: 50% 

 alcohol 1000 cc, glacial acetic acid 5 cc, corrosive sublimate 

 5 grams, picric acid i gram. This gave the most satisfactory 

 results and brought out many histological details that were not 

 demonstrable by the other methods. Gage's picric alcohol is 

 the basis of the mixture, the other parts being added to give a 

 more precise definition to the cells and their parts. For 

 delicate objects it is well to dilute the above with an equal 

 volume of water. 



The tissue according to its bulk is well fixed in from twelve 

 to twenty-four hours, and the sublimate and picric acid are 

 washed out in 50% and 70% alcohol. For staining, Delafield's 

 hematoxylin gave most excellent results ; contrast staining with 

 Van Gieson's picro-fuchsin gave most brilliant effects. Her- 

 rick's modification was found to work very satisfactorily. It 

 consists of adding an antiseptic tablet (corrosive sublimate 

 .5 gram and ammonium chloride .5 gram), to about half a 

 liter of the stain. Another satisfactory modification is the 

 addition of i cc. of glacial acetic acid and i cc. of a saturated 

 aqueous solution of corrosive sublimate to 100 cc. of the 

 hematoxylin. 



