ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 211 



The solution acts best at a temperature of about 35^ C, and the time 

 required varies from 10 minutes to about 12 hours, according to the 

 kind of pigment. The prolonged action of the fluid is not at all 

 detrimental to the eye-tissues. 



Technique for Malaria Blood.* — Dr. J. W. W. Stephens and Dr. S. 

 E. Christophers describe the following simple method for preparing and 

 staining films of malarial blood. The finger is pricked with a triangular 

 surgical needle, and a clean glass slide made to touch the exuding drop 

 of blood. The drop thus received on the slide is then spread by the shaft 

 of the needle in a broad even streak along the slide. On first touching 

 the drop with the needle-shaft, a little time should be given for the drop 

 to run along the needle for some distance by capillarity. The most 

 perfect films are thus obtained. The slides are then placed in a pot of 

 absolute alcohol for 5 minutes. The films are stained with a saturated 

 alcoholic solution of haeniatein. To every 10 ccm. of this solution are 

 added 50 ccm. of alum solution (alum 50 grm., water 1000 ccm.). The 

 slides are immersed in the solution for 5 to 20 minutes, or even hours. 

 The slide is examined by applying oil directly without the intervention 

 of a cover-glass. If it be required to preserve the specimen, the oil is 

 washed off with xylol, and the preparation mounted in balsam. The 

 slides, however, will keep for a year if merely wrapped in clean paper 

 and placed in a closed box. 



Cleaning Desmids. j — G. H. Bryan describes the procedure he adopts 

 for cleaning destnids. The apparatus consists of one or two saucers or 

 porcelain dishes, an old pomatum-pot, and a pen-" filler," while a gauze 

 strainer is useful for getting rid of large pieces of dirt. The material is 

 strained into a saucer, and after an interval not exceeding half a minute 

 the dish is inclined, a gentle rocking motion being given at the same 

 time. Along the edge of the receding water the desmids collect in a 

 bright green line or patch, from which they are picked up by the tiller. 

 They are next transferred to the pomatum-pot, and fixed with Zenker's 

 fluid. A repetition of the rocking enables the desmids to be again 

 collected and taken up in the filler, to be transferred to a dish containing 

 clean water, in order to remove the fixative. The washing, together with 

 the rocking, is repeated. The whole process takes from a half to one hour, 

 and this procedure involves less loss of specimens than the decautation 

 method. 



Method for Isolating Bacterial Flora from Water.ij: — K. Greig Smith, 

 when isolating the bacterial flora of the Sydney water supply, used 

 Abba's gelatin (Liebig's extract 6 grm., gelatin 150 grm., and distilled 

 water 1000 ccm.; after neutralising, 0*5 grm. anhydrous sodium car- 

 bonate are added) and dextrin-meat-agar. The latter is prepared by 

 dissolving 20 grm. of agar in 1000 ccm. of meat extract in the autoclave. 

 After clarification with white of egg, 10 ccm. of the mixture are pipetted 

 into warm water, and neutralised to phenolphthalein with tenth-normal 

 sodium hydrate. The sodium hydrate, together with # 5 grm. sodium 

 carbonate, is added to the bulk, and then 20 grm. of dextrin or gum 



* Roy. Soc. Reports to Malaria Committee, 3rd series, 1900, pp. 5-6. 

 t Journ. Applied Microscopy, iii. (1900) pp. 1026-7. 

 X Proc. Linn. Soc. N.S.W., xxv. (1900) pp. 438-40. 



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