688 SUMMARY OF CURRENT RESEARCHES RELATING TO 



older ones consist of cocci of very variable size, which are grouped in 

 Sarcina-packets and possess mucous walls. They are often brown or 

 black. This species oxidises numerous carbon compounds with the 

 formation of carbonic acid and water. It is macro-aerophilous. 



A. agilis was found in Delft canal water. It Las polar cilia and is 

 very motile. These bacteria are large and transparent, resembling small 

 Monads. They have a well-marked wall, protoplasm, nucleus, granules, 

 and vacuoles. Tbey grow well on various media, and especially well on 

 tap-water agar with 2 p.c. glucose and 0*02 p.c. K 2 HP0 4 . With salts 

 of organic acids they can produce a green or red diffusible pigment. 

 Gelatin is not liquefied. 



Influence of Microbes on the Development of Tadpoles.* — Mdme. 

 0. Metchnikoff has endeavoured to solve the much debated questions 

 whether microbes are or are not indispensable to animal nutrition and 

 development, and what part non-pathogenic microbes play in the intes- 

 tinal canal. Tadpoles were obtained under aseptic conditions and fed 

 on sterilised bread. Of 80 tadpoles, 31 died in a day or two ; in 42 

 cases the cultures therefrom gave evidence of bacterial contamination, 

 and only seven remained sterile. None of the 80 survived longer than 

 79 days. Five out of the seven sterile cultures lived for 63 days or 

 longer, while only seven out of the 42 reached this age. The non- 

 sterile became considerably larger and heavier than the sterile tadpoles, 

 the maximum weight and size of the latter corresponding to the minimum 

 of the former. From this the authoress concludes that microbes are 

 necessary to the life and development of tadpoles. 



Ripening of Cheese and the Role of Micro-organisms in the 

 Process. "f — F. C. Harrison, after recounting the results of previous ob- 

 servers from F. (John in 1875, states that the three following facts seem 

 well supported by good evidence and by trustworthy experiments. 

 (1) The enormous number of lactic acid bacteria in hard cheese, and 

 the very small numbers of liquefying or digesting bacteria. (2) The 

 existence of galactose, a natural enzyme inherent in fresh milk. (3) The 

 ability of rennet to cause the change of non-soluble nitrogenous pro- 

 ducts to soluble ones. 



Assuming that these facts are proved, the ripening of cheese may 

 be said to be caused by the digestive action of rennet on the insoluble 

 nitrogenous matter of the cheese, in the presence of acid formed by the 

 lactic acid bacteria. The large amount of acidity also prevents or in- 

 hibits the growth of other and perhaps undesirable species of bacteria. 

 As far as Canadian Cheddar cheese is concerned, the presence of galactose 

 appears to be of little importance. 



Photo-bacteria as a Reagent in the Investigation of the Chloro- 

 phyll Function. J — Prof. M. W. Beijerinek finds that photo-bacteria can 

 be used to show when the chlorophyll of leaves is functioning ; for if 

 leaves in contact with a culture of jmoto-bacteria are excluded from 

 any source of oxygen, the bacteria will only phosphoresce when the 

 chlorophyll is functioning. 



* Ann. Inst. Pasteur, xv. (J 901) pp. 631-4. 



t Trans. Canadian Inst., vii. (1901) pp. 103-34. Cf. this Journal, ante, p. 196. 

 X Proc. K. Akad. Wetensch. Amsterdam, iv. (1901) pp. 45-9. See Journ. Chem. 

 Soc, lxsx. (1901) Abstr. ii. p. 523. 



