116 SUMMARY OF CURRKNT RKSEARCHES RELATING TO 



New Medium for the Cultivation of Meningococcus.*— H. \Y. 

 Crowe says that with the following medium it is impossible to miss a 

 positive. It is easily prepared, and keeps well when tubed, though, in 

 common with other media, plates must be fairly fresh. It consists of 

 three parts of defibrinated bullock's blood, one part of trypsin agar 

 (Douglas) with 1 p.c. of glucose. The component parts are mixed in 

 sterile fashion at 50° C, poured into sterile plates or tubes, and steamed 

 for three days in succession at 60" C. for two or three hours, but raised 

 to 80° C. during ths last half-hour on the third day. The medium 

 should be dark brown and opaque, and should present a smooth glossy 

 .surface. It should be at least one-eighth to three-sixteenths of an inch 

 in thickness on plates. 



(2) Preparing Objects. 



Simple Device for Controlling the Movements of Paramoecia.f — 

 R. W. H. Row has found the following procedure give very successful 

 results. A small quantity of ordinary gum is painted on a glass slide 

 and allowed to become nearly dry ; a drop of water containing the 

 Paramoecia is then placed on the gum and covered in the ordinary \\ay 

 with a cover-glass. At first tlie gum will scarcely interfere with the 

 movements of the animals at all, but within a few minutes, as the gum 

 diffuses through the water, they will be seen to move more and more 

 slowly, and ultimately tliey will be unable to move at all. Finally, 

 the irritation caused by the gum will result in the discharge of the 

 trichocysts. By this method the normal shape and appearance are 

 retained for a long time, even when the animal has become stationary, 

 though the gullet tends gradually to disappear. 



C4D ^staining and Injecting:. 



Vital-staining of Insects by Means of Soluble Carmin.| — ■ 

 A. C. Hollande remarks that when insects are injected with an aqueous 

 solution of a carminate soluble in water, certain cells absorb the car- 

 minate in about twelve hours and are stained red. The absorbing cells 

 are the pericardial and the phagocytic leucocytes. The author then by 

 means of the following procedure rendered insoluble carmin soluble. 

 To 1 grm. of acid in a porcelain basin is added powdered carmin in 

 quantity sufficient to neutralize the acid. The mixture is diluted with 

 100 cm.^ of distilled water. It is then boiled for ten minutes and after- 

 wards filtered, and then volume is brought ^ap to 100 cm^. This solution 

 is used for injection ; it is very stable and neutral to litmus. Sulpho- 

 carmin and chloro-carmin are the examples given. The chloro- 

 carmin is quite innocuous in 1 p.c. aqueous solution. After injection 

 not only are the pericardial cells and the phagocytic leucocytes stained 

 red, but also the cells of the Malpighian tubes. After ingestion by the 

 insects it was found that the protoplasm of the foregut was deeply 



* Lancet, 1915, ii., pp. 1127-33 (6 ligs.). 



t Nature, 1915, p. 286. 



X Gomptes Rendus, clxi. (1915), pp. 578-80. 



