ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 511 



moss was a favourite shelter for Rotifera was rediscovered by Milne and 

 toy Zelinka independently about 188G, and it had mnce been extensively 

 .searched by several workers. Many new species of these animals have 

 thereby been discovered, notably by James Murray, until his loss in the 

 ill-fated Stephansson Expedition. With few exceptions the species 

 found in moss do not inhabit ponds or ditches. They belong mostly to 

 the Bdelloida, but some of the Floima frequently occur in mosses grow- 

 ing in wet places. Even mosses growing in dry positions (on walls, etc.) 

 are tenanted by many rotifers which require the presence of water for 

 active life, and this has become possible from the capacity of most 

 Bdelloid species to protect themselves against desiccation by covering 

 themselves by an air-proof coating of secretion exuded from their skins 

 (as shown long ago by Davis). Mosses are collected from anywhere and 

 from everywhere, either for examination at once or at a later date. Those 

 growing in wet places can be kept in good condition for several weeks, 

 those from dry positions for many months, if treated suitably. Before 

 examination they have to be soaked in added water until the rotifers 

 resume activity. The fullest details are given for this process and the 

 subsequent treatment of the specimens obtained. 



For identification most Bdelloida must be seen while feeding and 

 favourably placed, but when first selected they are frequently either so 

 timid that they remain contracted, or so excited that they march about 

 •continuously. A system has therefore been adopted of placing them in 

 small cells for a few days until their confidence is restored, when profit- 

 able examination can be made. The whole procedure is very fully 

 explained, and the various accessories employed are clearly figured and 

 •described. 



Cultivating Amoebae on Solid Media for Class Use.* — M. W. 

 Welch uses a medium which is composed of dextrin 10, dipotassium 

 phosphate 2, magnesium sulphate 0*2, calcium carbonate 0*2, agar 10, 

 ■distilled water 1000. The amoebge are fed on azotobacter obtained from 

 a poor soil. A number of trials may be necessary before an amcebae 

 which will feed on azotobacter is found. 



Apparatus for Isolation and Cultivation of Anaerobes, f — 

 A. R. Friel has devised the following simple anaerobic apparatus 

 {fig. 1). To expel the air, the apparatus is heated in the autoclave. 

 Air and steam escape through the cut E in the rubber tubing D 

 (Bunsen's valve). When the apparatus cools, the steam condenses and 

 atmospheric pressure closes the slit and prevents air entering. At the 

 same time water rises in the pipette J as far as the glass bead I. To 

 inoculate the culture tube A an emulsion of the material to be cultivated 

 is made in a tube of recently boiled broth or saline, and the end of the 

 pipette J is placed in it and the rubber round the glass bead I is made 

 oval by pressure with the finger and thumb. When the fluid has 

 ■entered the large tube the pressure is relaxed. 



If it be desired to isolate the various species of bacteria in a mixture, 



* Trans. Amer. Micr. Soc, xxxvi. (1917) pp. 21-5. 

 t Lancet, cxciii. (1917) p. 390. 



