374 SUMMAEY OF CURRENT RESEARCHES RELATING TO 



distilled water and then dehydrated as quickly as possible in absolute 

 alcohol, as this extracts the colour. The third procedure was to stain 

 first for a few days with Delafield and follow this with Apathy's haema- 

 tein. The sections were differentiated in 1 per thousand hydrochloric 

 acid-alcohol. The plasma stains used were acid rubin, differentiated 

 or not with acetic acid-alcohol or with picric acid. For double staining, 

 borax-carmine and bleu de Lyon. After fixation with osmic acid the 

 sections are examinable without staining, though safranin was employed 

 in some cases. For differentiating nerve-fibrils Apathy's gilding method 

 was used. 



Preparation of Radulse.* — K. Diederichs remarks that snails are 

 best killed with boiling water, and after removal of superfluous parts, 

 the head should be boiled in caustic potash solution until the soft tissues 

 can be easily removed from the radula. When thoroughly clean the 

 preparation may be mounted in glycerin or in isinglass jelly. If 

 mounted in balsam the preparation should be stained with some picro- 

 carmin solution, for which the formulae given in the April number are 

 suitable.f 



Fixing and Staining Phycochromacese.J — R- Hegler fixed the 

 material with saturated aqueous sulphurous acid 7 parts ; 94 p.c. 

 alcohol 93 parts, and after 12-14 hours washed it in alcohol. If there 

 were much lime, he washed in running water or even fixed with 5 p.c. 

 saturated ^0 2 solution, 95 p.c. distilled water. 



Formalin-alcohol (40 p.c. formalin 5 p.c. and 94 p.c. alcohol 95 p.c), 

 afterwards washing with 50 p.c. alcohol, sometimes gave good results. 



The fixed material was imbedded in paraffin and sections made, or 

 a small piece was squeezed flat between two cover-glasses. These 

 preparations were placed in 50, 75, and 94 p.c. alcohol, and then after 

 some days the cover-glasses were separated and placed in a mixture of 

 2 parts absolute alcohol, 1 part glycerin, and 1 part water. A third 

 method was to make cover-glass films and preserve in the above- 

 mentioned mixture. 



The following methods gave the sharper staining of the central 

 body : — Dissolve ammonia-alum 75 in water 750, and add glycerin 125, 

 alcohol 100, saturated alcoholic solution of hematoxylin 25. Expose 

 to light for several weeks and stain with 10 vols, to 100 vols. 1 p.c. 

 formalin for 24 hours. Wash for 24 hours in running water, and 

 differentiate in saturated alcoholic solution of picric acid 1 vol., water 

 1 vol., alcohol (94 p.c.) 2 vols, for a few seconds, wash in 75 p.c. alcohol 

 and examine under Microscope. Instead of picric acid, 1 per thousand 

 hydrochloric acid in 60 p.c. alcohol may be used. After differentiation 

 the preparations are washed till they become blue, after which alcohol, 

 toluol, dammar. 



Another method is to fix in S0 2 alcohol, immerse for 2-4 hours in 

 1 • 5 p.c. iron-alum solution, and then, without rinsing in water, to treat 

 with the following for at least 24 hours: — 1 grm. hematoxylin, 200 

 water, 4 ccm. formalin (shake and filter). The preparations are next 



* Zeitschr. angew. Mikr., vii. (1901) pp. 29-30 (1 pi.). 



t See ante, p. 255. 



% Jahrb. wiss. Bot., xxxvi. (1901) pp. 319-25 (2 pis.). 



