ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 623 



Chemical Changes produced by Coli-typhosus Group Bacteria.* — 

 H. Raistrick as the result of his experiments reports that histidine is 

 converted into urocanic acid (/3 - iminoazolylacrylic acid) in a medium 

 consisting of Ringer's solution and histidine by the following bacteria : 

 B. coli communis, B. typhosus, B. paratyphosus, B. enteriditis, a,nd 

 B. dysenterise. The change is represented by the equation C3H3N2 . 

 CH, . CHCNH^) . CO2H = C3H3N. . CH : CH . CO^H - NH3. 



Decomposition of Protein-substances through the Action of Bac- 

 teria.f— R. H. Robinson and H. V. Tartar have studied the chemical 

 changes that occur when a protein is acted on by certain organisms — 

 B. subtiUs, B. mycoides, and B. vulgaris (proteus) — present in most soils. 

 The percentage of nitrogen combined in various forms are estimated 

 before and after bacterial action by Van Sly he's method. 



The results indicate that all the forms in which nitrogen is com- 

 bined are changed, more or less, by the action of bacteria, and the 

 end-product ammonia is formed. The mono-amino-acid nitrogen and 

 diamino-acid nitrogen of the protein are the chief sources of the 

 ammonia produced,"but the action of the bacteria is not confined to one 

 particular form to the exclusion of the others. The rapidity of action 

 varies greatly with different proteins, casein showing no further change 

 after a few days, whilst giiadin continues to evolve ammonia after thirty 

 days. The reason for the arrest of bacterial action has not been .eluci- 

 dated ; it does not appear to be the formation of a toxic substance. 



The changes observed indicate that the bacterial decomposition of 

 proteins is effected by hydrolysis, with the formation of the amino-acids, 

 and subsequent degradation with the liberation of ammonia. 



Development of Reproductive Organs in Yeasts. t — K. Saito has 

 ascertained the action of various chemical agents on the development of 

 spores by the following three yeasts : Zygosaccharomycetes manchuricus, 

 Schizosaccharomycetes octosporus, and Saccharomycetes manchuricus. The 

 results indicate that the formation of spores only occur when the medium 

 in which the yeast-cell is grown contains members of definite classes of 

 substances. 



Cells of Zygosaccharomycetes when transferred to pure water do not 

 form spores. If, however, a carbohydrate or similar substance is present 

 spores are formed, and this formation of spores occurs more rapidly in 

 the presence of a simple monosaccharide than of a polysacchride or 

 carbohydrate derivative, such as dulcitol. The addition of a trace of 

 potassium phosphate and Witte's pepton accelerates the production of 

 spores ; ammonium salts, amino- and weak organic acids inhibit the 

 reproductive process. The concentration of the medium may be varied 

 within wide limits without entirely arresting the development of spores. 



* Biochem. Journ., xi. (1917) pp. 71-7. See also Journ. Chem. Soc, i. (1917) 

 p. 499. 



t Journ. Biol. Chem., xxx. (1917) pp. 135-44. See also Journ. Chem. Soc, i. 

 (1917) pp. 498-9. 



t Journ. Coll. Sci. Imp. Univ. Tokyo, xxxix. (1916) 3, pp. 1-73. See also Journ. 

 Chem. Soc, i. (1917) p. 499. 



