ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 395 



be repeated four or five times. The slide is then plunged into distilled 

 water, the section floats off, and then, after a short washing, is differen- 

 tiated in 60 per cent, alcohol, to which nitric acid in the proportion of 

 20 drops to 100 ccm. has been added. A second bath in acid-alcohol is 

 required to complete the differentiation. The acid is removed by wash- 

 ing freely in distilled water, and then the preparation may be contrast- 

 stained with very dilute aqueous solution of methylen-blue, thionin, or 

 iodine-green. After washing in water, the section is replaced on a slide, 

 mopped up, rapidly dehydrated with absolute alcohol, cleared up in 

 xylol, and mounted in xylol-balsam. The preparations keep well. 



Modification of Nissl's Method.* — Sig. G. Boccardi has modified 

 Nissl's method in the following way. Fixation in absolute alcohol for 

 24 hours or in 10 per cent, formalin for 12-24 hours, with consecutive 

 gradual transference to absolute alcohol ; paraffin imbedding. The 

 sections are stuck on the cover-glass with water. After removing the 

 paraffin with xylol, the preparations are transferred to absolute alcohol, 

 and then stained with the following mixture: — erythrosin 0'1 grm. ; 

 toluidin 0*2-0 '5 grm. ; water 100 grm. Though not absolutely neces- 

 sary, it is advisable to add 4-5 drops of aceton to the mixture. The 

 staining requires 15-20 minutes at ordinary room temperature, and 5 in 

 the thermostat at 37°, or one minute if heated over the flame. The pre- 

 parations are then washed in water for a few seconds, and immediately 

 afterwards differentiated in 0*5 per cent, alum solution. This takes a 

 few seconds or at most a minute. After having been washed in distilled 

 water, the preparations are passed through alcohol to xylol and mounted 

 in xylol-balsam. 



Point in the Technique of the Cox-Golgi Method, f— Dr. J. B. 

 Nicholls calls attention to the importance of immersing sections of 

 nervous tissue which have been treated by the Cox-Golgi method for a 

 few seconds in 50 per cent, caustic alkali solution. This not only ; 

 deepens the colour, but brings it out when the sections are apparently 

 unstained. 



Preparing Copepoda.J — Mr. C. D. Marsh collects copepoda in a 

 dredge, the mouth of which is covered with a cone of" coarse wire 

 gauze. The animals may be killed in some osmic acid solution ; alcohol 

 is, however, the best fixative and preservative. The specimens may be 

 stained in 1-3 days, by pipetting off most of the alcohol, and putting a 

 little picro-carmine in the bottle. The animals are best dissected on a 

 slide and in glycerin. Care must be taken to substitute the glycerin 

 gradually. The needles used should be ground flat so as to make 

 minute scalpels. The best mounting medium is Farrant's. 



Preparing Earth-worms for Sectioning.§— Mr. E. Pearl stupefies 

 the worms by placing them in 3 per cent, alcohol for an hour, and during 

 the next hour gradually raising the strength to 6 per cent. Some 6 per 

 cent, alcohol is then injected into the anus by means of a syringe. The 

 intestinal contents are loosened by rolling and pinching the worm 



* Monitors Zool. Ital., x. (1899) pp. 141-3. See Zeitschr. f. wiss. Mikr., xvi. 

 (1900) pp. 471-2. t Journ. App. Microscopy, iii. (1900) p. 674. 



t Op. cit., ii. (1899) pp. 295-6. § Op. ci*., iii. (1900) p. 680 



