ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 519 



blotting-paper and covering with a 10 p.c. solution of commercial nitric 

 acid. This serves to decalcify as well as to fix them, and also lessens 

 the susceptibility of Nissl's granules to take the stain. They are left 

 in the acid until decalcified (4K hours), and the acid is frequently 

 changed so as to keep it of as uniform a strength as possible. They 

 are then placed in 8 c.cni. of alcohol 90 p.c, 3 c.cm. of water, and 

 1 c.cm. of ammonia for 24 hours. If they turn brown, discard : this 

 is due to impure nitric acid or too long immersion. Again place in 

 alcohol for 6 to 12 hours, then in 1 c.cm. of HOI, 3 c.cm. of water 

 and 8 to 12 c.cm. of alcohol for 24 hours. Then alcohol again 

 for 10 to 24 hours, distilled water for 2 to 6 hours (not longer), 

 ammonium inolybdate, 4 p.c, for 24 hours. Dehydrate as rapidly as 

 possible and imbed in paraffin ; cut sections as thin as possible ; 

 attach the sections to the slides with Meyer's albumin ; wash out the 

 paraffin with naphtha and alcohol ; rinse the slide with distilled 

 water ; then cover the sections with distilled water and heat for 10 

 minutes at 50° to 60° C. The top of the imbedding bath is a very 

 good place for this. Pour off the water and cover with toludin-blue 

 1 in 4000 ; replace in the paraffin bath for 10 minutes ; dehydrate ; 

 clear and mount. Keep all the sections, and, if you are lucky, some 

 of them will be found to have the nerve fibres duly stained." 



Studying the Morphology of Spirochseta pallida.* — F. Krzystalowicz 

 and M. Siedlecki wash open sores or ulcers with sterilised water or salt 

 solution, but if the skin be unbroken the site of the lesion is cleaned 

 with soap and water and then with the alcohol-ether mixture. A 

 clear, slightly sanguinolent, fluid is obtained from open sores by squeezing 

 the borders of the lesion. When the surface of the lesion is dry and 

 intact, a blister may be raised by means of cantharides, ammonia, or 

 chloroform, or even by heat. When the lesion is deep-seated, e.g. 

 glands or gummata, juice may be withdrawn by means of a hypo- 

 dermic syringe. However obtained, the juice is spread on a slide, 

 dried in the air, and fixed with osmic acid vapour. Such films are stained 

 with Giemsa (1 drop to 1 c.cm. of water) for several hours, and after 

 washing with water are decolorised by immersion for several minutes 

 in 25 p.c. tannin solution. After this they are again washed with 

 water, while after this a rapid wash with absolute alcohol will not 

 damage the staining and helps to clean up the preparation. 



Instead of osmic acid, formol may be used for fixation ; the results 

 therefrom are not so good, but it has the advantage of allowing any 

 staining method to be applied to the films. 



Demonstrating Leucocytes in Tissues.! — H. Schridde fixes the 

 material in formol-Mliller, though other methods are also suitable. Thin 

 paraffin sections (5 /a) fixed to the slide in the usual way are placed for 

 20 minutes in a solution consisting of Giemsa to 1 c.cm. of water. After 

 washing in water they are mopped up with blotting-paper and then 

 transferred to water-free aceton. After about a minute they are placed 



* Bull. Internat. Acad. Sci. Cracovie, 1908, pp. 173-231 (2 pis.). 

 t Zentralbl. f. Allgem. Pathol, u. Pathol. Anat., xvi. (1905) pp. 770-1. See also 

 Zeitschr. wiss. Mikrosk., xxiii. (1906) pp. 212-14. 



