ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



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these actions automatically, and therefore operate the whole machine. 

 Thus the operator's other hand is free to look after the section-ribbon or 

 for other purposes. The essential part of the object-holder is a micro- 

 meter spindle gripped by Leitz' well-known forceps-nut. The spindle 

 itself glides without lateral disturbance in a swallow-tailed groove in the 

 base-plate and is clamped from below. The knife may be fastened 

 with one clamp or with two, and the knife below is provided with a scale 

 for controlling the knife-inclination. The pillars for knife-attachment 

 are connected with a broadened portion of the base-plate. The pillar 

 used for single-clamping is permanent, but that used for the second 

 clamp (fig. 14) works in a groove and is secured in its required position 



Fig. 14. 



by a butterfly-nut attached to its base. The knife can be raised by the 

 insertion of metal rings under the clamps. The author speaks highly of 

 the accuracy and uniformity of the sections obtained by this machine. 



Modification of Altmann's Method of Staining Chondriosomes.* 

 H. Kull gives the following procedure: — Fixation in 3' 5 p.c. bichro- 

 mate of potassium, 80 c.cm. + 20 c.cm. 40 p.c. formalin for twenty-four 

 hours, after which the pieces are transferred to the bichromate solution 

 without formalin for three to four days. The pieces are then washed 

 in running water and paraffin sections made. Celloidin sections may 

 be prepared by Rubaschkin's method (see this Journal, 1907, p. 683). 



Another method of fixation by means of osmic acid mixtures gives 



* Anat. Anzeig., xlv. (1913) pp. 153-7. 



