342 SUMMARY OF CURRENT RESEARCHES RELATING TO 



and inoculated them with extract of beau-roots, of nodules, and of the 

 adhering soil, and carried on observations over a period of two weeks. 

 Assimilation took place in each case, and the results were very similar. 

 The greatest assimilation was noted in the extract of stems and leaves,, 

 and the least in the peat extract. 



Alinit-Bacillus Beta.* — Fr. Bayer describes a new bacillus, Alinit- 

 bacillus Beta, which is found associated with the ordinary Alinit bacillus 

 {Alpha) in all humous soils that have responded to the application of 

 alinit. The new bacillus does not by itself assimilate free nitrogen, but 

 it increases the assimilating power of the A-bacillus, and the simul- 

 taneous action of the two benefits all crops. The author notes the desira- 

 bility of adding a certain amount of carbohydrate (e.g. solution of 

 molasses) to the soil when applying alinit. 



Luminous Bacteria.! — Barnard gives a short resume of the group of 

 photogenic bacteria, twenty-five species of which have been isolated up 

 to the present time from sea- water. He supports the opinion that the 

 emission of light by these organisms is merely the result of cell-meta- 

 bolism comparable to the production of heat by other forms of life. 

 The most suitable medium for the cultivation of these bacteria is prepared 

 by adding 2 • 6 p.c. sodium chloride, * 75 p.c. magnesium chloride, and 

 • 3 p.c. potassium chloride to ordinary meat-peptone broth. Free oxygen 

 should be bubbled through the medium during the growth of the organ- 

 isms, or frequent agitation resorted to, in order to obtain the maximum 

 luminosity. The optimum temperature of photogenic bacteria occurring 

 in the northern latitudes is about 15° C, although they are able to grow 

 and remain luminous at 0° C. Those found in the tropics grow at a 

 somewhat higher temperature, but none require blood-heat for their 

 optimum temperature. The spectrum of luminous bacteria gives a 

 bright band between F and G. The author includes some striking 

 illustrations of cultivations of photogenic bacteria, which have been 

 photographed entirely by their own light. 



Variability of Micro-Organisms.| — Ruzicka compared and con- 

 trasted B. pyocyaneus and B. fluoresceins liquefaciens, bacilli which he 

 considers are very closely allied. Failing in his endeavours to place 

 the B. fluorescens liquefaciens under the conditions in which the B. pyo- 

 cyaneus exists in nature, he restricted his observations to pure cultiva- 

 tions incubated in the laboratory for long periods, under such conditions 

 with respect to temperature and moisture as would obtain in wound 

 infections. After this treatment, some of the cultural reactions resembled 

 those of the original strain ; others, however, became modified and re- 

 sembled those of the B. pyocyaneus in forming more pigment than at the 

 room temperature, and growing sparingly on glycerin-agar. These 

 new characters wero retained for months. 



On the other hand, a typical strain of the B. pyocyaneus was kept in 

 water, and the conditions varied by exposing the cultivations to, and 

 protecting them from light and air, without the cultural characters 

 undergoing any important change. Those freely supplied with air were 



* Bied. Centr., xxxi. (1902) pp. 12-4. See Jnurn. Chem. Soc, 1902, Abstr. ii. 

 p. 164. t Nature, lxv. (1902) pp. 536-8. 



% Arch. f. Hygiene, xxxvii. p. 1. See Bot. Centralbl., lxxxviii. (1901) p. 122. 



