ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 761 



Method for Collecting the Gas of Fermentation.* — A. Cache 

 recommends the following method : Having poured the fluid medium 

 into an ordinary test-tube, he places in it a small short test-glass 

 inverted, and brings the whole into the autoclave ; during the process 

 of sterilisation, all the air in the small tube has escaped, and, after 

 cooling, it is seen to be full of medium. On testing sugar bouillon 

 inoculated with an organism capable of causing fermentation, the gas 

 produced will collect in the inverted tube. 



(2) Preparing^ Objects. 



Examination of the Spermatozoa of Ascaris megalocephala.f — 

 L. Scheben gives the following details of the method employed by him 

 in the examination of the male genital organs of Ascaris tnegalocephala : 

 The specimen is obtained as fresh as possible, and put into the fixing 

 solution, a mixture of 50 parts of absolute alcohol, 50 parts of mercuric 

 chloride, and 2 parts of acetic acid, or picric acid as used by Boveri ; or 

 Zenker's solution may be used. The material is cut up into small pieces, 

 and left in the fixing solution for 12 hours, and after removal of the 

 mercury by means of iodine solution, it is placed in 60 p.c. alcohol, and 

 from this it is transferred to alcohols of progressively higher percentages 

 up to absolute alcohol, in which it should not be allowed to remain too 

 long when once the desired hardness has been reached. The object is 

 now placed in xylol, or better, in pure chloroform, covered by a layer of 

 absolute alcohol, to protect the specimen that floats on the surface of the 

 chloroform, from the air ; when the object is sufficiently penetrated, the 

 alcohol can be pipetted off, and the specimen is transferred to a mixture 

 of xylol, or chloroform and paraffin, and after about half an hour it is 

 imbedded in pure paraffin. The imbedding process lasts about 4 hours 

 at 6o c C. Sections were then made ranging from 4 /jl to 10 p. Good 

 staining was obtained by Heidenhain's hasniatoxylin method, and 

 counterstaining with a light green ; simple picrocarmine staining also 

 answered well ; the author also stained with anilin dyes, using the 

 double stain of Heidenhain's hematoxylin and Bordeaux red. Besides 

 making sections, he also examined the contents of fresh genital glands 

 from the living animal, by means of a warm stage, in albumen-glycerin 

 or in a weak solution of sugar ; or he fixed the contents expressed on to 

 a cover-slip, in osmic acid vapour, or by the method suggested by 

 Van Beneden and Boveri, and mounted in glycerin. 



Methods of Examining- the Eyes and Frontal Organs of Branchio- 

 pods.J — M. Nowikoff finds that Gilson's fluid is the best for fixing these 

 objects, but he also got good results with sublimate acetic, or with 96 p.c. 

 alcohol. For the thicker sections, that served to show the topographical 

 relations, he stained with borax-carmine and \ p.c. Lyons blue, or borax- 

 carmine, osmic acid, and wood vinegar, after Schuberg, or with Delafield's 

 hematoxylin and picric acid fuchsin, according to Van Gieson. This 

 last is also very good for fine sections ; but he found that for these, in 

 order to show the plasma structure, Butschli's or M. Heidenhain's 



* Centralbl. Bakt. Kef., l te Abt., xxxvii.(1905) p. 49. 

 t Zeitschr. wiss. Zool., lxxix. (1905) p. 400. % Tom. cit., p. 433. 



