ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 237 



results were also obtained with Zenker's and Bourn's fluids. Solutions 

 containing osmic acid were found to be unsuitable. For staining the 

 sections, Heidenhain's iron - hematoxylin or Benda's modification 

 thereof, were mostly employed ; previous treatment with Bordeaux red 

 was sometimes satisfactory. The Biondi-Heidenhain triple stain gave 

 beautiful results, but the colours faded in about a year. 



Cover-glass preparations were made by mixing a small quantity of 

 sperm taken from the testis, or from the receptaculum seminis, with a 

 little sea-water, and fixing for several minutes in osmic acid vapour. 

 These were stained by the Biondi-Heidenhain triple stain, or by 

 Ranvier's gold and formic acid method. 



The author strongly recommends that the living cells should be 

 examined in serum, sea-water, or other isotonic fluid, as thereby impor- 

 tant details are easily seen, the which are lost by fixation. The figures 

 given on the plates were drawn with the Zeiss apparatus under magnifica- 

 tions of 1400 and 8500. 



Fixing Pyrosoma.* — A. Korotneff treats the eggs and embryos of 

 Pyrosoma for a good half -hour with half saturated solution of sublimate 

 in sea-water. After careful washing, the material is immersed in 

 Perenyi's fluid for an hour, and is then transferred to alcohol. Staining 

 with alum-carmin was found to be useful, and immersion of the material 

 in 5 p.c. formalin occasionally had the effect of completely dissolving the 

 yolk and setting free the embryo. 



Demonstrating Structure of Nephridia of Arenicola. f — R. S. 

 Lillie fixed adult material for 15-30 minutes in Hermann's fluid, and 

 then transferred to Whitman's modification of Merkel (equal parts of 

 1 p.c. chromic acid and 0*25 p.c. platinum chloride) for 1-3 hours. 

 The material was next washed, and then transferred to alcohol as 

 usual. The treatment with Hermann's fluid prevents excessive blacken- 

 ing, and the reduced osmium may be further removed by immersing the 

 sections for some hours in a mixture of 1 part hydrogen peroxide and 

 3 parts alcohol. The most satisfactory stain was Heidenhain's iron- 

 hematoxylin countered with erythrosin. The best mounting medium 

 for examination with oil-immersion objectives was found to be inspis- 

 sated cedar-oil. 



Larvae were best fixed by immersing them for 2-5 minutes in 

 Hermann's fluid, followed by Merkel's fluid for 1-3 hours. Young 

 larvae of the swarming stage were treated with Hermann's fluid for 

 two minutes, followed by Merkel's for 1 hour. Such larvae should be 

 imbedded as soon as they are fixed, otherwise the yolk becomes very 

 brittle. 



Demonstrating the Endings of the Auditory Nerve in Petromyzon 

 fluviatilis.J — R- Krause fixed the material in Flemming's, Hermann's, 

 Zenker's and Carnoy's fluids. Exposure to the vapour of a mixture of 

 equal parts of 4 p.c. osmic and acetic acids was specially favourable, the 

 preparation being transferred after 10 minutes to 40 p.c. alcohol. 



* Mitth. Zool. Stat. Neapel, xvii. (1905) pp. 295-311 (3 pis.). 



+ Tom. cit., pp. 341-405 (4 pis.). 



t SB. k. Preuss. Akad. Wiss., xlviii. (1905) pp. 1017-19. 



