ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 163 



obtained by killing tbe eyes first witb one-tenth per cent, chromic acid 

 for half an hour, allowing them to remain in one-half per cent, for 24 hours, 

 one-tenth per cent, for 24 hours, and finally one-fifth per cent, for 4=8 hours 

 or more. 



Demonstration of Bile-capillaries.* — For the demonstration of the 

 biliary capillaries, Dr. M. Miura used the following methods: — A small 

 piece of liver, after having been in Miiller's fluid for 2-5 days, is washed 

 with ordinary water and laid in distilled water for 3-5 hours. It is then 

 transferred for 2-3 hours to a 15 per cent, watery grape-sugar solution. 

 It is next placed for two or three days in a • 1-0 • 2 per cent, solution of 

 gold chloride. The gold solution is to be changed two or three times. 

 Finally the preparation is again left for two or three days in the grape- 

 sugar solution, but without access of air, until it assumes a dark violet 

 or black colour. The bile-capillaries are stained a purple red. 



Preparing Horse-hoofs.f — In Dr. C. Norner's investigations, directed 

 chiefly towards the discovery of nerve-fibres, the hard corneous layers were 

 first removed from the hoof, and then small pieces of the softer tissues 

 were cut out and placed in osmic acid and gold chloride. Pieces of tissue 

 were placed in osmic acid (1 : 100) for 24:-48 hours, they were then 

 washed and stained in picro-carmine {in toto). In using 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 picrocarmine. 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 en- 

 couragingly of either method, as he found that both were unsatisfactory. 



For examining the histological structure of the hoof, pieces of the softer 

 parts were stained in toto in Eanvier's picrocarmine, 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 cut and then stained. 



Showing Mitosis in Brain of Tadpole.^ — Prof. A. Eauber has in his 

 researches found the following methods most successful in displaying the 

 nuclear division in the nervous system of frog embryos. For hardening, 

 1/3-1/2 per cent, chromic acid, and alcohol, or Flemming's mixture of 

 chromic, osmic, acetic acids and water, were found most satisfactory. For 

 staining, safranin solution or gentian-violet, or picrocarmine and haema- 

 toxylin, alone or successively, yielded the best results. 



Method of Studying Development of Genital Organs of Pulmonata.§ 



— In his account of the development of the generative apparatus of Stylom- 

 matophorous Pulmonata, Dr. J. Brock states that Agriolimax agresiis is a 

 satisfactory species to cut into sections for the purpose of orientation when 



* Virchow's Arch. f. Pathol. Anat, xcix. (1885) pp. 512-21 (1 pi.). 



t Arch. f. Mikr. Anat., xxviii. (1886) pp. 171-224 (1 pi.). 



t Ibid., xxvi. (1886) pp. 622-44 (1 pi.). 



§ Zeitschr. f. Wiss. Zool., xliv. (1886) pp. 338-9. 



M 2 



