432 SUMMAEY OF CUERENT RESEARCHES RELATING TO 



is then tran'feferred to a second bath of absolute alcohol with 0*75 p.c. 

 ammonia for 24 hours at the same temperature. The tissue is then 

 carefully washed in distilled water and placed in a 1 p.c. solution of 

 silver nitrate, and kept in the dark at 32° C. until it assumes a golden- 

 brown colour. It is then washed in distilled water, and transferred 

 to the following developing solution. It is important to note that this 

 manipulation must be done either in the dark or with a red light. 

 Developing solution : pyrogallic acid 1 grm., formalin 5 c.cm., absolute 

 alcohol 10 c.cm., distilled water to 100 c.cm. After the tissue has 

 been 24 hours in this solution at a temperature of 32° C, it is washed 

 in distilled water and then transferred to 50 p.c. alcohol, and carried 

 through the ordinary process of dehydration. This stain colours the 

 nerve-fibres dark brown or black, while the rest of the tissue is bright 

 yellow. The nerve-fibres alone are clearly defined, and for this reason 

 many photographs made of sections stained in this way seem slightly 

 bhirred. The materials used were the ovary of the cat, dog, and rabbit. 

 The organs were removed from the animals some hours after death, as 

 it is found to be better than using the tissues absolutely fresh. 



Staining Trypanosomes.* — A. Ponselle first treats the dried smear 

 with absolute alcohol 50 c.cm. plus tincture of iodine (French Codex) 

 10 drops for 5 minutes. The smear is then washed with absolute 

 alcohol and allowed to dry. The preparation is then covered with a 

 layer of some serum, e.g. horse serum heated to 56°. After about 5 

 minutes the preparation is washed in distilled water, and then stained 

 for 15-30 minutes with Giemsa (1 drop to 1 c.cm. of distilled water). 

 Finally, the preparation is washed with distilled water and allowed to 

 dry. This technique does not give better results than other methods 

 for staining trypanosomes drawn from the blood, but is specially 

 adapted for these organisms obtained by cultivation. 



Demohstrating the Clear and Cloudy Fibres of Striated Muscle.t 

 W. Ewald fixes in formalin and cuts frozen sections. The sections are 

 stained with iron-haematoxylin, alizarin-blue, or with sudan. The 

 illustrations show^ distinctly the difference between tlie clear and cloudy 

 fibres. The appearances are better seen when the muscle is cut trans- 

 versely. 



Celloidin sections were also used, and other stains such as Biel- 

 schowsky's and Van Gieson's were employed, but the results from the 

 three first mentioned, either alone or in combination, seem simpler and 

 more useful. For the author's views, and those of P. Schaefer in the 

 same number, the original should be consulted. 



(6) Miscellaneous. 



Marking Slides. J — To mark spots on a microscopical preparation, 

 Y. Salkind recommends the following device. A glass disk furnished 

 with an ebonite ring is made so as to fit the top of the condenser, and 



* C.R. Soc. Biol. Paris, Ixxiv. (1913) pp. 1072-3. 



t Abhandl. Senckenberg. Naturforsch. Gesell., xxxi. (1912) pp. 109-50 (5 pis.). 



i Zeitschr. wiss. Mikrosk, xxix. (1913) p. 544. 



