ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 821 



jelly is then squeezed under a pressure of about 80 kilos, between thick 

 layers of bibulous paper, in order to remove as much water as possible. 

 The acid-celloidin is next mixed with twice its bulk of methyl-alcohol, 

 whereby it is quickly dissolved. A piece of enamel, 0*5 mm. thick, 

 takes about six days to decalcify. If gas bubbles be given off the pro- 

 cess is going on too rapidly. The author alludes to previous communica- 

 tions, for which see this Journal, 1908, pp. 775, and 1905, p. 764. 



Fixation and Staining of Glycogen.* — F. Zieglwallner describes 

 fixation and staining methods for the simultaneous demonstration of 

 glycogen and fat, and gives the following formulas : — 1. One p.c. chromic 

 acid solution in 84 p.c. alcohol, 15 ; 2 p.c. osmic acid, 4 ; acetic acid, 1. 

 The solution should be prepared immediately before use. 



2. Saturated sublimate solution, 20; 2|p.c. osmic acid, 20; acetic 

 acid, 10 ; absolute alcohol, 50. This fixes small pieces in from 8 to 12 

 hours. On removal the pieces are washed for 24 hours in 50 p.c. 

 alcohol, to which a few drops of tincture of iodine have been added. 

 In order to retain the blackening it is advisable to convert the osmium 

 into sulphide by treating the sections or pieces with 70 p.c. alcohol, to 

 which a small piece of Na 2 S has been added. 



3. By saturating a solution with formula very similar to No. 2 with 

 dextrose, another fixative which gives fair results is obtained. 



4. 10 p.c. trichlor-lactic acid for 3 to 4 hours, followed by 50 p.c. 

 alcohol. 



5. Trichlor-lactic acid, 9 ; 2 p.c. osmic acid, 24 ; acetic acid, 9 ; dis- 

 tilled water, 58. In this small pieces remain for 10 to 12 hours, after 

 which they are thoroughly washed in 50 p.c. alcohol. 



Various methods of staining glycogen are then alluded to, the best- 

 being Bleu-de-Lyon, as it gives considerable contrast. 



Studying Amoeba, f — B. Puschkarew pipettes off from a " zoological 

 culture " the amcebas, in company with algte and bacteria, on to an agar- 

 plate. After 6 or 7 hours, a piece, which should not exceed 1 c.cm., is 

 cut out. The piece is placed on a Hansen's slide and a clean cover- 

 glass imposed. After \ hour, during which time the amcebas will have 

 crawled on to the cover-glass, the space between the ring of the slide 

 and the agar slip is filled with fixative, the cover-glass not being re- 

 moved. The fixative used was either sublimate-alcohol or 2 p.c. osmic 

 acid ; the former being allowed to act for 20 to 30 minutes, the latter 

 for 10 to 20. The fixative is then removed with a pipette and re- 

 placed with iodin-alcohol or 50 p.c. alcohol : the former after sublimate, 

 the latter after osmic fixation. After allowing these reagents to act for 

 30 to 60 minutes, the cover-glass may be removed. The cover-glass is 

 then washed in water. It should be mentioned that no procedure will 

 get rid of all the bacteria, and these are sometimes very frequent. The 

 preparations may then be stained by the Romanow r sky-Giemsa method, 

 or with Heidenhain's iron-lnematoxylin. 



The author's illustrations are extremely effective. 



* Zeitschr. wiss. Mikrosk., xxviii. (1911). 



t Zeitschr. wiss. Mikrosk., xxviii. (1911) pp. 145-50 (2 figs.). 



