and Laboratory Methods. 1763 



coming from tearing, but still tissues occasionally show this fault. Further help 

 is now gained by infiltrating in such a vacuum as can be obtained by the use of 

 the pump. Any trace of the volatile liquid employed (toluol, xylol, chloroform) 

 can be removed in such a chamber and a more solid, uniform paraffin block 

 results. It has been possible by these means to cut the embryonic cartilaginous 

 membranes of the spinal cord in a faultless series of sections 4-5 ^ in thick- 

 ness. Also the notocord of Petromyzon with its hard envelope, in its connec- 

 tion with the spinal cord, spinal ganglia, and surrounding musculature, has been 

 cut into sections of equal or greater thinness. It was found that a different 

 procedure was best according to the use of chloroform, xylol or toluol. With 

 chloroform the material is passed into a warm chamber in a mixture of paraffin 

 and chloroform, then for an equal length of time in pure paraffin, and afterwards 

 it is put into the vacuum. If xylol or toluol is used, material is put directly 

 from the liquid into pure paraffin and into the vacuum ; only with extremely 

 delicate tissues is it necessary to have an intermediate medium. On pumping 

 out the air an active generation of gas results as can be seen by the bubbles 

 formed. These gradually become smaller, and when they cease the embedding 

 is completed. a. m. c. 



Godlewiski, J. Ueber die Entwicklung des „ , ^ i • • i t • 



quergestreiften musculosen Gewebes. Bull. Embryos of the guinea pig, rabbit, 

 de r Acad, des Sc. de Cracovie, Classe sheep, and mouse were fixed whole in 

 math, et natur. 146, igoi. ^ ,^ ^ , , , i- • , i 



Carnoy-Van Gehuchten's liquid, and 



in sublimate-acetic, embedded in paraffin (52°, melting point), and cut in a con- 

 tinuous series from 5-10 pi in thickness, fastened to the slide with water and 

 stained. Heidenhain's iron-hematoxylin was used with eosin or bordeaux-red for 

 a protoplasmic stain. Many sections were treated with hemalum-eosin or 

 vanadium-hematoxylin (after Cohn). Heidenhain's hematoxylin made visible 

 the first appearance of the fibrillae and their subsequent differentiation. In con- 

 nection with eosin or bordeaux-red the nerves and their courses can be beauti- 

 fully demonstrated. a. m. c. 



Pranter, V. Ein billiger Ersatz fiir Deckgliis- Gelatin paper was suggested as a sub- 

 ser. Zeitschr. f. wiss. Mikros., 18 : 159-161, gtit^j^g foj. ^^^^ expensive cover-glasses 

 1 90 1. . . 



of large sizes. This substance is com- 

 posed of a pure gelatin, almost colorless, quite transparent, with a smooth 

 surface. Paper-like sheets of 60 x 40 cm. are used in many of the arts as a pro- 

 tection against dust. It is soluble in water, glycerin, weak acid, and alkalies. 

 Insoluble in strong alcohol, ether, chloroform, xylol, benzine, fatty and etherial 

 oils. Sections in canada balsam or damar can be covered by pieces cut to the 

 necessary size, and the oil immersion can be used without difficulty. These 

 gelatin covers were used for temporary mounts ; for permanent preparations 

 they are less suitable, as heat and dampness causes wrinkling. This may in 

 part be avoided if a moderately thick varnish is applied, and the surface well 

 pressed down with blotting paper moistened in xylol. Preparations so mounted 

 keep for a year or more perfectly well, while others not so protected spoil in a 

 few days. For cleaning the surface soiled by the fingers a little benzine or xylol 

 is used. These covers only in part replace glass, but prove very serviceable for 

 large sections and temporary preparations. Griibler & Co. of Leipsic keep this 

 substance in large pieces, and in the usual cover-glass sizes. a. m. c. 



