108 SUMMARY OK CUfillENT LIESEABCHES RELATING TO 



water are placed in Frcudenrcich's flasks, and just before inoculation a 

 drop of ammonia sp. gr. 0*90 is added. 



Demonstration of Enzymes.* — S. L. Schouten gives a method for 

 more quickly demonstrating enzymes than that of Fermi. He mixes 

 water saturated with thymol, 7£ per cent, gelatin, and an equal quantity 

 of cinnabar. The solution, which is red, is distributed into test- 

 tubes. By rotating the tubes under a stream of water, a thin layer of 

 gelatin is formed above a thicker one. "When the fluid which is to be 

 examined for the presence of enzyme is put into the tube the action 

 takes place readily on the thin layer, and the result is more easily dis- 

 covered owing to tho red colour of the solution. This method was 

 adopted for examining enzymes of the Saprolegniaceae. 



Cultivation Medium for Cheese Bacteria.|— F. W. J. Boekhout and 

 J. J. Ott de Vries, in their investigation on the ripening of Edam cheese, 

 used cheese-gelatin which Avas prepared as follows : — Pieces of cheese 

 were ground up fine in a mill and a definite quantity (lj times its 

 weight) of water added. The mixture was macerated for two hours at 

 40° and then heated to 50°, being stirred the while, so that the insoluble 

 and partly soluble constituents might sink to the bottom. The super- 

 natant fluid was then poured off and allowed to stand for some hours. 

 The scum, which is composed of fat and albumen, was then skimmed off, 

 and the residue filtered. The filtrate or cheese-broth was worked up 

 into cheese-gelatin by the addition of 10 per cent, gelatin. This medium, 

 suitable for aerobic and anaerobic cultures, contains no milk-sugar and 

 is of acid reaction, thus fulfilling the conditions requisite in cheese- 

 ripening investigation. 



Cultivation of Rhizobium leguminosarum. J — R. Greig Smith has 

 obtained fairly luxuriant cultures of Rhizobium leguminosarum in a 

 gelatin medium containing glucose and inorganic salts, and also on a 

 medium composed of faintly acid agar (2 p.c.) glucose (2 p.c.) and in- 

 organic salts (CaCl 2 ar d KH 2 P0 4 ), nearly neutralised with KOH. In the 

 latter medium there is no nitrogen except that which may be present as 

 impurity in the washed agar, the glucose, or the tap-water. He has 

 also grown the organism in an agar-free fluid medium prepared exactly 

 as the agar medium. Such a fluid, after inoculation, becomes turbid, 

 and forms a slight sediment of organisms, together with a bulky zooglcea 

 cloud or sedimentary film. The experimental flasks were found to con- 

 tain exactly the same amount of nitrogen as the control flasks, hence no 

 fixation of nitrogen could have occurred. 



(2) Preparing 1 Objects. 



Handy Method of Preparing Slides and Slips for taking Blood 

 Films. § — W. L Braddon draws attention to a simple method of pre- 

 paring slips and slides for blood-examination. (1) A slip is placed on 

 a slide in such a position that one of its edges coincides exactly with 

 that of the slide. Then, for temporary use vaselin, for permanent pur- 



* Kouk. Akadem. v.Wetensch. Amsterdam, 1901. See Centralbl. Bakt, 1" Abt.,, 

 xxx. (1901) p. 780. t Centralbl. Bakt., 2" Abt., vii. (1901) pp. 817-33 (1 pi.). 

 X Proc. Linn. Soc. N.S.W., xxvi. (1901) pp. 15.'-5. 

 § Journ, Tropical Med., iii. (190(1) p. 110. 



