1084 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



of heating in water to about 80° C, and then after cooling slowly, 

 treating with the usual grades of alcohol. Good results are obtained 

 with Perenyi's fluid, which renders the yolk less brittle. Osmic acid 

 does not penetrate the chorion, and chromic acid or acid alcohol are 

 not easily soaked out on account of the thickness of the chorion. 



Borax-carmine is, on the whole, the best staining fluid. It is 

 difficult to make the dye penetrate the chorion, and, after hatching, 

 the cuticula forms a similar obstacle. This difficulty may be over- 

 come by prolonged immersion in the staining fluid. In some cases 

 seventy-two hours were required to obtain a sufficient depth of colour. 

 In order to avoid maceration, which would result from so long con- 

 tinued immersion in a weak alcoholic dye, the staining process may 

 be interrupted at the end of every twenty-four hours by transferring 

 to 70 per cent, alcohol for an hour or more. 



After most methods of hardening the yolk becomes very brittle, 

 and the sections crumble. This diificulty may be overcome by col- 

 lodionizing the cut surface before making each section, in the manner 

 described by Dr. Mark.* 



Balkwill's Foraminifera Slides. — Various " triumphs of mount- 

 ing •"' have been issued from time to time, including the well-known 

 arrangements of the scales of butterflies, but Mr. F. P. Balkwill must 

 be considered to have carried off the palm by his slides of Fora- 

 minifera which he commenced to issue now some years ago. On a 



Fig. 249. 



Fig. 250. 



plate only 2^ in. by 1^ in. no less than 220 different collections of 

 species of Foraminifera are arranged and named. Fig. 249 shows the 

 slide in natural size, with the 220 divisions. It has not been possible 

 to reproduce the photographed names, but fig. 250 enlarged 4 times 

 shows how they are pliced. 



Preparing Leaves to show Starch-grains. t — A very interesting 

 experiment, showing the influence of light upon the formation of 



* Ainer. Natural., xix. (18S5) p. 628. Seetliis Journnl, ante, p. 737. 

 t Cf. Amer. Mon. Micr, Jouru., vi. (1885) p. 178. 



