ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 227 



by heat, aud the contents incorporated in a double agar medium. When 

 cultivated thus upon a medium composed partially of its own products 

 this bacillus becomes profoundly altered. The culture acquires a 

 resemblance to those of actinomyces. The powers of liquefying gelatin 

 and of forming spores are lost, and the bacillus acquires a capsule, 

 possibly in order to protect itself from the deleterious effect of the 

 suljstances produced by its own metabolism. 



Growth of AlgsB in Red and Blue Light.* — G. A. Nadson culti- 

 vated Stichococcus bacillaris upon Beijeiinck's agar medium, in test-tubes 

 exposed to red and to blue lights. Control-cultures were grown in day- 

 light. No growth took place in the dark. Sodium bichromate solution 

 was used as red-yellow light-filter ; for the blue, use was made of an 

 ammoniacal copper solution. In red-yellow light, growth was affected 

 quantitatively and qualitatively, degenerative changes in the cells of the 

 organism being very pronounced. Blue light had little deleterious effect 

 either upon the nature or amount of growth. Successive generations in 

 blue light showed increasing strength of growth, whereas those in the red 

 showed progressive diminution and disorganisation. 



Influence of Temperature upon Bacterial Flora of Milk.f — ^Y. B. 

 Luxwoolda has investigated tlie relative rapidity of multiplication shown 

 by certain organisms naturally occurring in milk when the fluid is kept 

 at various temperatures. When milk is rapidly cooled nearly to 0°C., 

 the growth of organisms is for a time inhibited, but after this period 

 certain undesirable organisms from manure and unclean water, such as 

 Bacillus coU and B. proteus, multiply. Such organisms are capable of 

 growing and developing their toxic products without altering the ap- 

 pearance or taste of the milk. Lactic acid bacteria are inhibited. It is 

 therefore undesirable to keep milk for long periods under these con- 

 ditions. Milk that has been obtained under correct hygienic circum- 

 stances will remain in a more satisfactory condition. At 20° C. the lactic 

 acid bacteria will dominate the situation. B. fiuorescens Uguefaciens ai&o 

 grows well. B. coli and its allies fall into the background. Between 

 these temperatures the author has studied the behaviour of the milk- 

 flora at 10° C, 13° C, and 15° C. . 



Streptothrix leprae.^ — A. G. R. Foulerton, after the preliminary re- 

 mark that the generic terms Streptothrix, Actinomyces, Oospora, and 

 Nocarclia are synonymous, proceeds to discuss the nature of the leprosy 

 parasite. He supports the view that this is, in fact, a streptothrix, whose 

 fragmentation products, acid-fast rods, are the so-called lepra bacilli 

 encountered in leprous granalomata. Cultivations from these upon arti- 

 ficial media soon show disappearance of the acid-fast property and 

 acquirement of morphological and staining characters associated with the 

 streptotrichese. Fragmentation of this form will also produce the 

 diphtheroid forms described by some observers. In the author's view, 

 the acquirement of acid-fast properties is favoured by a parasitic 

 existence. 



* Centralbl. Bakt., 2te AM. xxxi. (1911) pp. 286-7. 

 t Centralbl. Bakt., 2te Abt. xxxi. (1911) pp. 129-75. 

 t Brit. Med. .Joufu. (1912) i. pp. 300-2. 



