ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 539 



the yeast-cell, also comprises three chapters in which the morphology and 

 life-history of the yeasts and the anatomy and the chemistry of the 

 yeast-cell are dealt with in turn. 



The general student will find much that is useful in the book, which 

 is well illustrated with figures from works of Brefeld, Zopf, Hansen, and 

 other mycologists. 



Schizomycetes. 



Thermophilous Bacteria.* — Mile. Tsiklinsky has investigated a 

 number of bacteria which have an optimum temperature about 55° C. 

 and a maximum between 60° and 70° C. These bacteria, as earlier 

 observations have well shown, are very widely distributed in nature, 

 e.g. in the soil, both at the surface and at a considerable depth, in 

 rivers, in dust, in milk, in the excrement of animals, in the mouth and 

 throughout the digestive canal of man, and even in freshly fallen snow. 

 The author has investigated five thermophilous bacteria from the hot 

 water of the thermal springs of the island of Ischia, but most of her 

 observations were made on the thermophilous bacteria found in me- 

 conium, in the faeces of infants only a few days old, and in the fasces 

 of adults. From these three sources about twenty bacteria are described, 

 to most of which no names are given. A form called Thermostrepto- 

 thrix vulgaris was isolated from soil, and from the same source a thermo- 

 philous conidia-bearing fungus was isolated, to which the name of 

 Thermomyces lanuginosus was given. This curious fungus grows best 

 between 42° and 60° C, and is capable of only slight development at 

 37° C, and of still less at the ordinary temperature. The paper ends 

 with a discussion of the value or otherwise of the bacteria found in the 

 alimentary canal of man and animals. 



Accumulation Experiments with Denitrifying Bacteria.f — G. van 

 Iterson, jr., describes the results of a series of experiments in which 

 access of air was partly or completely prevented. He has succeeded, by 

 cultivating in solutions of organic salts and nitrate, in bringing many 

 denitrifying bacteria to a more or less perfectly pure culture. Of these 

 experiments three always gave constant results, producing respectively 

 Bacterium Stutzeri Neum. and Lehm., B. denitrojiuorescens sp. n., and 

 B. vulpinus sp. n. The first named deserves attention on account of 

 the unique structure of its colonies (as figured). The second species is 

 the first example of a denitrifying non-liquefying fluorescent bacterium. 

 B. vulpinus is a brown-red pigment-bearing species ; the pigment forms 

 only in the light. B. Stutzeri and B. vulpinus behave towards free 

 oxygen like aerobic spirilla, the third species like an ordinary aerobic 

 bacterium. 



The author finds that denitrifying bacteria are generally distributed 

 in canal and sewage water. They can, even with the slightest quantity 

 of various organic substances, cause the disappearance of determined 

 quantities of nitrate with development of free nitrogen. In one and 

 the same culture medium where nitrification is produced during aeration, 



* Bull. Soc. Imp. Nat. Moscou, 1902, pp. 380-467 (10 tables and 2 pis.). 

 t Proc. K. Akad. Wetensch. Amsterdam, v. (1902) pp. 148-62 (1 pi.). 



