450 SUMMARY OF CURRENT RESEARCHES RELATING TO 



ihrix scopulorum, &c.) tlie authors find a kind of reproductive cells, which 

 they call conidia, differing from ordinary spores in preserving the appear- 

 ance of the vegetative cells, and multiplying indefinitely in the manner of 

 Chroococcus. 



The rest of the present instalment of the paper is occupied hy a mono- 

 graph of the Kivulariacese contained in the different French herbaria, 

 which the authors divide into three subtribes, Leptochseteae, Mastigotrichere, 

 and Rivulariefe, and ten genera, viz. Lejptochaete, Amjjhithrix, Calothrix, 

 Dicliotlirix, Polt/thrix, Sacconema, Isactis, Bivularia, Gloeotrichia, and Bra- 

 chytrichia. Of these Polythrix and Isactis are exclusively marine, Gloeotri- 

 chia exclusively fresh-water ; the other genera comprise both marine and 

 fresh-water, including five brackish si)ecies. The total number of species 

 described is 59, of which several are now described for the first time. 



Effects of Solar Light on Bacillus anthracis.* — M. S. Arloing, who 

 has already announced that spores of Bacillus anthracis sown in small 

 quantities in a clear culture-solution are killed by two or three hours' 

 exposure to the sunlight of June or July, notices the criticisms that have 

 been made by MM. Nocard, Duclaux, and Strauss, and then gives an 

 account of the later experiments which he has instituted. He finds that 

 under conditions in which it is impossible for a mycelium to arise, the 

 spores sown in the fluid are sterilized by the sun in a short time, which 

 varies with the season of the year. The sun does destroy the spores placed 

 in water, but it only does so after a longer period of time than is necessary 

 to eifect their death in a suitable fluid such as soup. Further investigations 

 are necessary to determine the influence of liquid screens interposed between 

 the spores and the sun ; and to these the author intends to devote himself. 

 What has been done is sufiicient to give a hint as to the apj)lication of the 

 results to hygiene ; it would be well to expose to the rays of the sun, without 

 any shelter, regions where the spores of micro-organisms have been deposited. 



Bacillus Brassicae.f — Dr. G. Pommer found in decoction of cabbage 

 leaves, in addition to Bacterium megatherium and other small Bacteria, a 

 Schizomycete characterized by mycelia in its vegetative condition, and 

 which is propagated by endogenous spores inclosed, after germination, in a 

 distinct spore-case. 



The vegetative forms derived from cultivation show more or less 

 distinct markings along the course of the mycelia, the thickness of which is 

 0" 00091-0 •0012 mm. The sparseness or closeness of the sowing and the 

 consistence of the nutritive medium appeared to exert some influence on 

 the form of the mycelium. If thinly sown, straight or wavy lines of 

 threads without loss of continuity are develoj)ed ; but when more 

 closely packed, the lines become more curved and spiral. Cultivation 

 on agar-agar produced straight bundles of filaments, while within the 

 medium tortuous masses of straight, wavy, and short threads were formed. 

 Deprivation of air was found to be a principal cause of involution, and 

 occurred in the worn out and spore-forming filaments. In the latter case 

 a complete disapj)earance of the protoplasm took place ; in others, changes 

 occurred in the plasma, together with swelling up of the membrane. 

 Spores originate only with access of air, and at first appear as greyish balls. 

 Fully formed spores are oval, being about • 0009 mm. broad, and from 

 0*0012-0 '0015 mm. long. At a temperature of 33° C. they are formed in 

 sixteen to twenty-four hours ; at ordinary temperature, in double the time. 

 In a short joint there is one spore ; in the larger ones sometimes two, and 

 their position is usually terminal. As the spore germinates, it increases 



* Comptes Reudus, civ. (1887) pp. 701-3. 

 t MT. But. Inst. Graz, i. (1886) pp. 93-112. 



