18 JOURNAL OF THE [January, 



Meeting of December i8th, 1885. 

 The President, Mr. C. Van Brunt, in the chair. 

 Thirty-one persons present. 



OBJECTS exhibited. 



1. Protococcusviridis from Central Park, N. Y., and its vicinity : 

 by E. B. SouTHWiCK and P. H. Dudley. 



2. Eozoon Canadense from Petite Nation, Canada: by A. Wood- 

 ward. 



3. Silicified Wood from Fredericksburg, Va.: by A.Woodward. 



4. Surface of Amphibius iiiiperialis, a beetle, from South 

 America : by M. H. Eisner. 



5. Embryo of Chick, after 48 hours' incubation ; mounted by 

 Prof. H. L. Smith : by F. H. Leggett. 



PROFESSOR H. L. SMITH'S NEW HIGH-REFRACTIVE MOUNTING 



MEDIUM. 



President Van Brunt : " Prof. H. L. Smith has devoted much 

 time to this subject, and the number of substances he has ex- 

 amined is very great. He has given the formulae of many com- 

 pounds of a high refractive index — a sulphur compound — an 

 arsenical compound — stannous-chloride and glycerine. Also 

 stannous-chloride and glycerine gelatine, and others, the most of 

 which have not stood the test of time. 



" How far this new compound will answer the purpose time 

 only can determine, although the probabilities of permanence 

 are in its favor. 



" The stannous-chloride and glycerine compound is permanent 

 unless too much of the salt has been dissolved in the glycerine. 

 In such a case it is apt to crystallise on the slide after mounting. 

 If too little is used in an effort to mount forms in a medium of 

 lower refractive index, the material is too fluid, and the forms 

 move. The addition of gelatine is objectionable for several 

 reasons. 



'' This new medium, is entirely different from the others in 

 having a new material, boro-glyceride, for the base. This 

 is in its glacial condition and quite hard. Prof. Smith 

 uses it with one-half pure glycerine ; that he calls a 

 50 per cent, solution. Mr. Booth states that it is simply a solu- 

 tion of 92 parts of glyceride and 62 parts of boracic acid, nearly 



