ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



379 



Microscopical Sections through both Cerebral Hemispheres.* — G. 

 Bonvicini prepares his material by putting it into solution containing a 

 potassium chromate (4 p.c.) and chromium sulphate (2*5 p.c.) for a 

 period varying from a fortnight to two months, according to the size of 

 the pieces. At first the solution is changed weekly. If the whole cere- 

 brum is to be so treated, the ventricles are injected with 10 p.c. formalin 

 by means of a serum syringe. After the chromate stage, the brain is 

 slung for six or eight days in a large vessel containing formalin. The 

 brain so prepared is then cut into slices by means of a macrotome 

 devised by the author (fig. 50). This instrument consists of a wooden 

 base H 1? upon which a wooden platform H can be moved by a screw, 



Fig. 50. 



controlled by the milled head T. To the base is hinged a glass plate G, 

 which can be moved through 90° into the position G 1 . The platform 

 H carries a stout vertical metal bow B, which guides the knife. At K, 

 where the knife would strike the platform H, a strip of cork is inserted 

 to prevent injuring the blade. The brain is placed on the board H, 

 and pushed through the bow B, as far as the glass plate G in its vertical 

 position will allow. The distance of the plate G from the bow B, and 

 consequently the thickness of the slice cut, is controlled by the screw- 

 head T. The surface of these slices may be stained and examined, or 

 fine sections may be cut by means of a microtome. 



* Zeitschr. wiss. Mikrosk., xxvi. (1909) pp. 410-18. 



