Litei'ary Notices. xxxi 



in these tests, Menidia notata and Fundulus hereroclitus, both small 

 species, and the initial after the serial number in each case indicates 

 which of the two species was employed in that test. All specimens 

 were adult unless otherwise stated. 



I. — FIXATION IN NITRIC ACID MIXTURES. 



Summary. — None of the mixtures containing nitric acid, including 

 several not mentioned above, gave a satisfactory fixation either of the 

 medullary sheaths of the nerves or of the general tissues, and in most 

 cases subsequent staining by the Weigcrt methods is impossible, either 

 because the tissue will not take up the stain or because in decolorizing 

 it bleaches uniformly. 



II. — FIXATION IN PICRIC ACID MIXTURES. 



ix F. A small specimen was treated for 8 days with, 

 Picric acid, saturated in water, 90 cc. 

 Acetic " (glacial), i cc. 



Formalin, lO cc. 



For complete decalcification further experience shows that a longer time, at 

 least two weeks, is necessary. Sections were mordanted for 45 minutes in a 4 

 per cent, solution of iron alum, stained in a )A per cent, solution of hasmatoxylin 

 in water for one hour and decolorizized in 2 per cent, iron alum. The fixation 

 is good and the axis cylinders are well differentiated. The medullary sheaths 

 are, however, not well preserved and are stained scarcely at all. 



14 M. The specimen was immersed for one month in the following 

 mixture : 



Picric acid, saturated in water, 90 cc. 



Iron alum, cryst., 4 g. 



Formalin, 10 cc. 



Decalcification was complete and the tissue very well preserved. But sec- 

 tions stained in ^4 per cent, solution of hematoxylin in water for from 15 min- 

 utes to 5 hours and decolorized in 2 per cent, iron alum failed to differentiate 

 the nerve sheaths properly. The whole tissue decolorized nearly uniformly. 

 Other sections which were treated with Delafield's hematoxylin failed to take 

 up any of the stain. Upon staining with Ranvier's picro-carmine the sections 

 show excellent preservation of all the tissues, though the nerve sheaths are 

 badly shrunken. 



15 M. Sections from the same block as the last, mordanted for 16 hours in 

 5 per cent, potassium bichromate, stained for 6 hours in Weigert's hxMnatoxylin 

 and decolorized in Weigert's decolorizer did not differentiate the medullary 

 sheaths and were in worse histological condition than in the previous case. The 

 long soaking in aqueous solutions seems injurious, the nerve sheaths especially 

 being more shrunken. 



Summary. — Several other picric acid mixtures were tried, includ- 

 ing two of vom Rath's formulce ; but in no case were the nerve sheaths 

 properly preserved, nor did they give satisfactory Weigert stains. I 



