ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



375 



washed in running water for an hour. Any surface deposit is removed 

 bv means of 1 per thousand HOI alcohol. Differentiation with 0*5 p.c. 

 iron-ammonia-alum solution or with hydrochloric and alcohol or picric 

 and alcohol. Next frequent washing, and mouuting as hefore. 



Preparing Liver of Mollusca.* — P. Enriques experienced much 

 difficulty in fixing tho liver of Mollusca, especially in warm weather. 

 Most of the ordinary fixatives have a solvent action on these organs, 

 so that the cells disappear and the hepatic framework only remains. 

 The most satisfactory fixatives appear to have been, saturated aqueous 

 solution of sublimate in ■ 5-1 p.c. NaCl and in 5 p.c. acetic acid ; 

 chrom-osmic-acetic acid and Miiller's fluid. By partially drying in the 

 air fresh tissue, and then imbedding in gum and glycerin or in syrup 

 and glycerin, decent sections were obtained. If these sections had to 

 be treated with aqueous fluids they were stuck on the slide with a 

 solution of gelatin at 50°-60°. The best staining results were given by 

 haemalum and thionin. 



(3) Cutting-, including- Imbedding and Microtomes. 



Standing's Imbedding Microtome. — This microtome (fig. 89), 

 made by Messrs. E. and J. Beck, consists of a ball of wood surmounted 

 by a tube, in the interior of which 

 the object to be cut is imbedded. 

 Over the tube is screwed a small 

 table which is lowered to the requisite 

 amount to cut the section. In the 

 centre of the ball is a plug, by means 

 of which the specimen is located in 

 a convenient position preparatory to 

 cutting. The whole of the upper 

 portion being removable, the imbed- 

 ding can be filled in from below. 



Slide-Brake of Jung's Micro- 

 tome, t — This is an accessory in- 

 vented by the Heidelberg firm, with 

 the assistance of Prof. Heidenhain, 

 for increasing the stability of the 

 It had been found that, 

 to the thickness of the oil- 

 layer or in the case of sections of 

 unusual size or hardness, the section 

 thicknesses were not perfectly uni- 

 form and sometimes exhibited varia- Fig. 89. 

 tions of ' 5 fx. The contrivance for 



rectifying this is called the slide-brake (Schlitlenbremse) and will be 

 understood from the following description : — On each slide-track there 

 is now attached a bar (a, fig. 90), and the slide c runs along and 

 presses upon this by the into position of a reel, or roller, b. This roller 

 is fastened to the slide, not directly, but in the following way (fig. 91). 



* Mittheil. Zool. Stat. Neapel, xv. (1901) pp. 281-407 (3 pis.). 

 t Xeitschr. f. wis*. Mikr., xviii. (1901) pp. 138-40 (2 figs.). 



slide-gea 



owing 



