116" The Microscope. 



washed and stained in picro-carmine {in toto). In iising the gold 

 chloride, the fresh pieces were first rendered sufficiently transparent 

 by soaking for one to five minutes in one-third formic acid. They 

 were then transferred to a gold chloride solution (1 : 100 or 1 : 200) 

 for 20 hours. After washing, the gold is reduced by putting the 

 pieces in a weak solution of formic acid for 24 hours in the dark. 

 They were then hardened in absolute alcohol and stained in toto in 

 picro-carmine. The sections were first examined in dilute glycerin, 

 and those showing numerous nerves were placed, after staining, in 

 dilute picric acid, then passed through alcohol to oil of cloves, and 

 mounted in balsam. In preparations thus treated the nerves, stained 

 dark violet to black, show up against the red background. The 

 author does not speak encoivragingly of either method, as he found 

 that both were unsatisfactory. For examining the histological stnic- 

 ture of the hoof, pieces of the softer part were stained in toto in 

 Ranvier's picro-carmine, and were then hardened in alcohol. The 

 sections were then placed in water, slightly acidulated with picric 

 acid, and mounted in balsam or in formic- acid glycerin; or the pieces 

 were first out and then stained. — Journal R. M. Society. 



Pkepaking the Bacillus of Lustgaeten. — M. M. Alvarey and 

 Tavel, {Arch, de Physiol, xvii, 1885), have modified Lustgarten's 

 method as follows : Instead of sulphuric acid they use 2 per cent, 

 oxalic acid; a stay of two hours in the warm soliition they find suffi- 

 cient, and they double stain with rosin, picro-carmine, and safranin. 

 They approve De Giacomi's method if the iron chloride be strongly 

 acid. Against Lustgarten they maintain that the sj'philis bacillus, 

 like that of tubercle, strongly resists decolorization by acids (33 per 

 cent, nitric, hydrochloric and suljihuric acids.) The authors, how- 

 ever, mention a difference between the two bacilli, which is, that 

 Lustgarten's microbe becomes immediately unstained by alcohol after 

 treatment with acid: the acid must therefore be well washed out in 

 water, if the color is to be retained. — Journal R. M. Society. 



Methods of Preparing Eyes of Mammels. Birds, Molluscaxs, 

 AND Anthropods. — The eyes of certain mammals used by Dr. A. 

 Dostoiewsky (Arch. f. Mikro. Anat. xxviii, 1886). were hardened in 

 Miiller's flu.ids for periods varjung from a few days to several 

 months. Many of the eyes had previously been placed for 24 to 48 

 hours in a 2 or 3 per cent, chromic acid solution. For cutting, the 

 anterior half of the eye was embedded in celloidin used in three 

 different strengths, (thin, medium, and thick). In each of these so- 



