ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 611 



place. Then the tray is transferred to a dish of cold water or alcohol 

 standing at the end of the embedding stage, and into which it is 

 immersed as soon as the paraffin is cooled snfficiently to prevent the 

 breaking of the surface by the water. 



The use of this embedding stage secures ^ood embedding, because 

 the paraffin is melted clear to the bottom of the tray, and thus orienta- 

 tion IS made easy. 



(4) staining- and Injecting-. 



Method of Staining Flagella.* — L. Tribondeau, in collaboration 

 with M. Fichet and J. Dubreuil, has evolved a simple procedure for 

 staining bacterial flagella. The bacteria are grown on Martin's agar 

 2 p.c. (slightly alkaline) in Petri dishes. After twelve hours' incubation 

 a colony is picked off and emulsified in distilled water. Cover-slips are 

 boiled in bichromate of potash 50 grms., sulphuric acid 100 grms., 

 water 1000 grms., and then washed in tap-water ; dry and flame in the 

 Bunsen burner, wash the flamed surface with distilled water, and dry 

 vertically without wiping. A drop or two of the bacterial emulsion is 

 allowed to spread itself over the cover-slip, and when the film is dry it 

 is fixed rapidly with absolute alcohol. Staining : Solution of tannin, 

 10 parts per 100 in distilled water 1 part, saturated solution of potash 

 alum in distilled water 2 parts. Boil rapidly, add 0'5 c.cm. alcoholic 

 solution of crystal violet (stock solution, 2 parts in 10 of alcohol 1 part, 

 absolute ethyl-alcohol 10 parts), mix and bring again to the boil, mix 

 again and cover the surface of the films very rapidly and allow to act 

 for from fifteen to thirty seconds. Wash rapidly under the tap, dry and 

 examine with the oil-immersion lens. The flagella are coloured blue- 

 violet. 



Cultural Vital- staining of Bacteria. f — T. Iwao says that the 

 following medium gives good results : To hot filtered agar, made 

 alkalin with sodium carbonate, are added • 3 of " eosinsaures " 

 methylen blue. The agar solution is carefully shaken and then dis- 

 tributed in test tubes, 10 c.cm. in each. After this they are sterilized 

 for one hour at lOO'' C. The staining of the bacteria, especially of the 

 coli group, is good, the granules coming out well. 



(5) Mounting, including- Slides, Preservative Fluids, etc. 



Slide for Examining Small Pond Life.ij: — E. M. Nelson describes 

 a new form of slide, and also describes the apparatus required. First, 

 an oil-immersion sub-stage condenser on dark-ground illuminator. 

 Second, two slips, 3 by 1^-, cemented along their bottom edges to 

 make a ledge. A drop of the gathering is put with a pipette in the 



* C.R. Soc. Biol. Paris, Ixxix. (1916) pp. 710-16. 



t Acta Schol. Med. Univ. Imp. Kioto, i. (1916) pp. 251-62 (1 pi.). 



J English Mechanic, Sept. 29, 1916, p. 191. 



