Notes upon the Brain of the Alligator. 131 



with that of the higher types. The important position occupied 

 by these reptiles with relation to their own class and the Sauropsida 

 generally, because of their antiquity, isolation, comprehensiveness, 

 and especially their resemblance to birds in very important struc- 

 tural points, adds importance to otherwise trivial details. It soon 

 appeared that, entirely aside from the problems in the interest of 

 which the investigation was made, the intrinsic importance of 

 the subject warranted a more detailed treatment than at first 

 expected. 



The notes, at first made for a special purpose, have, therefore, 

 been extended and connected by subsequent observations in order 

 to secure a measure of completeness and sequence in what must, 

 nevertheless, betray the fragmentary and sketchy origin. The 

 material upon which this paper rests is derived from four small 

 specimens of alligator, none of which exceeded eighteen inches in 

 length, all of which were received through the kindness of friends. 

 Three of these were furnished by Mr. Gray, of the College Hill 

 Conservatory, while a much regretted hiatus was filled through the 

 kindness of Mrs. Stevens, of Columbia. 



The methods employed were simple, though, unfortunately, in 

 several cases, accidents prevented the complete success of the 

 operation. The fixing medium in each case was a dilute chrom- 

 acetic acid bath, in which the brains were left for twenty-four 

 hours. This has proven for small brains the most uniformly suc- 

 cessful of all media. If care is taken to remove excess of acid, 

 there is little difficulty in staining permanently. The specimen is 

 then placed in fifty, seventy, eighty and ninety per cent, alcohol 

 successively, with intervals of twenty-four to forty-eight hours. 

 The best sections for all purposes were stained in section with 

 aqueous haematoxylin, but the process is tedious and makes it 

 difficult to secure consecutive series. Staining in toto with alum 

 cochineal is excellent for many purposes. The entire brain is 

 placed in a strong solution of the stain from seventy-five per cent, 

 alcohol, remaining twelve hours, and afterward is hardened in alco- 

 hol as usual. Alcoholic cochineal and carmine preparations pro- 

 duced only a diffuse and highly unsatisfactory stain, as did the 

 alcohol haematoxylin, so highly recommended. Analine blue-black 

 possesses no advantages over haematoxylin. In spite of experi- 

 mental difficulties, fairly useful series were made, embracing the 

 entire brain cut transversely, longitudinally-horizontally and longi- 



