ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 105 



Contributions to Vegetable Pathology.* — M. J. H, Wakker dis- 

 cusses the malady caused by Bacterium Eijacintlii. The bacteria which 

 may be regarded as the cause of this disease are more or less cylindrical 

 and colourless, and may be found by myriads in the yellow mucilage of 

 the bulbs that are attacked. The spores of B. HyacintJii are slightly 

 longer than they are broad, and are bluish in colour. 



Another disease of hyacinths and allied plants, caused by Peziza 

 huTborum, is also described. The spores of this fungus are ovoid and 

 colourless, and are contained in asci ; they show two bright bluish spots, 

 each situated at the same distance from the extremities. 



Purple Bacteria and their relation to Light.f — Prof. Th. "W. 

 Engelmann, who has long interested himself in the behaviour of bacteria 

 towards light, has continued his observations in the same field, taking 

 for his subjects those forms which are well known, and have been 

 thoroughly described, such as Bacterium pTiotometricum, roseo-persicinum, 

 ruhescens, sulfuratum, Beggiatoa roseo-persicina, and several others. In 

 these, most of which belong to the sulphur bacteria, a purplish pigment, 

 bacterio-purpurin, is diifused throughout their plasma. The behaviour 

 of these organisms towards light was found by the author to depend not 

 on the sulphur, but on the bacterio-purpurin. 



With regard to the direct influence of light, it was found that the 

 rapidity of the movements was increased by illumination, and, per contra, 

 ceased in the dark ; and that purple bacteria were diiferently affected 

 by light of different wave-lengths. 



With regard to the spectrometric investigation of the colour of 

 purple bacteria and the measurement of the absorption of the dark heat- 

 rays, the original must be consulted. 



The author also discusses the excretion of oxygen by these purple 

 bacteria while they are in the light, and the dependence of their growth 

 on light. 



With regard to bacterio-purpurin, he comes to the conclusion that it 

 is a true chromophyll, in so far as the absorbed actual energy of light 

 is changed by it into potential chemical energy. 



Pathogenic Bacterium found in Tetanus, i — Drs. Belfanti and 

 Pescarolo describe a bacillus which they have obtained from the dis- 

 charges of a person who died presumably of tetanus. Injection of this 

 material into mice produced tetanic symptoms in from 10 hours to 10 

 days. From this material the authors isolated a bacterium which, injected 

 into rabbits, mice, sparrows, &g., caused death preceded by paralytic or 

 convulsive phenomena. Cultivated on the usual media, the development 

 of this bacillus was examined in hanging drops, wherein it appeared as 

 a rodlet, rather longer than broad, and resembling the bacillus of fowl- 

 cholera. The ends are rounded. It is mobile even at a temperature of 

 23^-25° C, and it multiplies by fission. It was stained well by the 

 usual methods, and was decolorized in 2 minutes when Gram's method 

 was used. The colonies are white or whitish yellow, and do not liquefy 

 gelatin. 



* Arch. Xeerland.. xxiii. (1888) pp. 1-71. 



t Bot. Ztg.. xlvi. (1S8S) pp. 661-9, 677-S9 (2 figs.). 693-701 (1 fig.), 709-20. 

 Cf. this Journal. 1888, p. 473. 



j Centralbl. f. Bakteriol, u. Paiasiteuk., iv. (1SS8) pp. 513-9. - 



