ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 387 



50 c.cm. After rilling up to 150 c.cm. with distilled water, it is 

 filtered, and to every 40 c.cm. of the filtrate, 3 drops of pure hydrochloric 

 acid are added. After the precipitate has subsided, the clear orange- 

 red fluid is ready for use. 



Paraffin sections are incubated in the stain for 18-24 hours, and 

 then, after a washing with distilled water, are treated for h-2 minutes 

 with 1 p.c. iron-alum solution, which, should they turn black, is changed. 

 The sections are again washed and then passed through graded alcohols 

 to xylol and balsam. 



For staining en masse the pieces are incubated for 48 hours, and 

 mordanted with the iron-alum solution ; if a 2k p.c. be used, then for 

 15-60 minutes ; if a 1 p.c, for 12-24 hours. 



The preparations show the chromatin of the nuclei black, the 

 protoplasm grey, the yolk granules red, nucleoli red. 



If the centrosomes are to be stained, the following modification 

 must be adopted. The sections are stained for one day in the cochineal 

 decoction, and, after a short mordanting, are placed in Weigert's haemato- 

 xylin solution for two days, after which they are differentiated in 2£ p.c. 

 iron-alum solution. 



The material used was chiefly the larvae of rana esculenta, and the 

 best fixative was found to be Zenker's fluid. 



Demonstrating Fatty Infiltration in Tissue.* — P. Foa has aban- 

 doned the method of fixing the material with Flemming's fluid and 

 staining with safranin and picric-alcohol, for Marchi's method, which 

 he finds more effective. 



The pieces are placed for 3 or 4 days in Muller's fluid, and then 

 transferred for a similar period to the osmic-bichromate mixture. On 

 removal they are washed and then hardened in alcohol. By this pro- 

 cedure the elasticity of the tissues is well preserved, the osmic acid 

 penetrates thoroughly, and the sections can be stained with hematoxylin 

 and eosin, or by Van Gieson's method. 



Kappers, C. U. A. — Ein kleiner apparat fur die Gesamtbehandlung vieler Objekt- 

 trager. (A clamp for holding together and simultaneously treating several 

 slides.) Zeitschr. wins. Mikrosk., xxi. (1904) pp. 1S5-8 (1 rig.). 



Lichtenbebg, S. — Objekttragergestell zur gleichzeitigen Behandlung zahlreicher 

 Schniffe. (A frame for the simultaneous treatment of numerous sections.) 



Tom. cit., pp. 321-4 (1 fig.). 



(5) Mounting, including- Slides, Preservative Fluids, &c. 



Copal as a Mounting Medium. f — J. G. P. Powell recommends 

 copal dissolved in absolute alcohol for mounting vegetable sections. 

 Though somewhat difficult to prepare, it acts well. It is not suitable for 

 diatoms. Apparently it takes about two months to dissolve properly. 



Method for Removing Small Quantities of Centrifuged Deposit.} — 

 O. C. Van Walsem uses a Pravaz's syringe, and fills the canula and 



* Atti R. Acad. Sci. Torino, xl. (1905) pp. 65-78 (1 pi.). 



t English Mechanic, lxxxi. (1905) p. 133. 



j Zeitschr. wiss. Mikrosk.. xxi. (1901) pp. 172-4 (1 fig.). 



2 D 2 



