ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 115 



with pure serum and ascetic fluid, at length deposits a whitish powdery 

 sediment. The medium may be sohdified by the direct addition of 2 p.c. 

 agar. 



Tetravaccine : Typhoid + Paratyphoid A + Paratyphoid B + 

 Cholera.* — A. Castellani and E. W. Mendelson report very favourably 

 on the results obtained with their tetravaccine in Serbia, where they 

 gave protective inoculations to some 50,000 persons. Each c.cm. of the 

 compound vaccine contained 500 million typhoid organisms, 250 million 

 each of paratyphoid A atid B, and 1000 million cholera organisms. 

 0*5 c.cm. of the vaccine was given subcutaneously, a similar dose being 

 repeated a week later. The inoculations were quite harmless, and pro- 

 tective substances were developed against the four organisms, the amount 

 of agglutinins present being practically the same as in conti'ol individuals 

 inoculated with typhoid, paratyphoid A, paratyphoid B, and cholera 

 monovaccines. The authors are of opinion that the tetravaccine should 

 be used as a matter of routine to inoculate the troops taking part in the 

 present war, its use rendering it possible to give by a simple and rapid 

 procedure a contemporaneous protection for the four maladies. 



Examining Faeces for Protozoa.f— C. M. Wenyon recommends that 

 thin films be used for examining fresh faeces, and in dealing with 

 encysted forms a small drop of Gram's iodine solution should be mixed 

 on a slide with a small quantity of faeces (iodine 1, iodide of potassium 2, 

 distilled water 100). A cover-glass should be imposed and the prepara- 

 tion examined at once. This procedure renders the nuclei quite distinct. 



For permanent preparation the following method has given good 

 results. A thin smear of the f seces is made on a cover-glass, and then is 

 dropped without drying, film-side downwards, on to a fixing fluid. A 

 good one consists of 2 parts of aqueous sublimate and 1 of alcohol. The 

 cover-glasses float on the surface of the fixative and are allowed to 

 remain there for 20-30 minutes. They are then removed and placed in 

 a Petri dish of 30 p.c. spirit (this time film-side up) in order to remove 

 the sublimate. After a few minutes' washing in this manner in several 

 changes of the alcohol they are placed in distilled water. They are then 

 stained best with iron hematoxylin. The films are left to soak in a 

 4 p.c. solution of iron alum, they are then rapidly washed in distilled 

 water, and then placed in Heidenhain's hgematoxylin. After some hours 

 the black films are washed and then immersed in 1 p.c. iron alum solu- 

 tion to differentiate. The differentiation must not be carried too far, 

 and the films must be examined every few minutes in distilled water 

 under one-sixth objective. After proper differentiation the films are 

 dehydrated in alcohol, passed through xylol, and mounted in balsam. 



The author remarks that it is essential to have constantly at hand an 

 eye-piece fitted with a micrometer scale, the size of the divisions of 

 which is known in microns for each power of the Microscope and for a 

 definite tube length. 



"&• 



* Brit. Med. Journ. 1916, ii., pp. 711-3. 

 t Lancet, 1915, pp. 1173-83 (1 pi.). 



I 2 



