690 SUMMARY OF CURBENT- RESEARCHES RELATING TO 



Beggiatoa roseo-persicina Zopf. Previously described as Cohnia 

 roseo-persicina. Known in the coccus, bacillus, leptothrix, and 

 spii'illuni-forms. 



Action of Heat on Pathogenous Bacteria.* — A. Chauveau has 

 carried on a series of experiments on the effects of a high temperatui-e 

 both on the develoi^ment and on the infectivity of pathogenous bacteria. 

 For this piu-pose sterilized infusion of meat was infected with fresh 

 cattle-distemper blood, and the vessel placed in a thermostat with a 

 uniform temperature of 42°-43' C, from which it was transferred, 

 after about twenty hours, to another with a temperature of 47^ C, and 

 left there for some hours. The bacteria were found, from this treat- 

 ment, to have suffered no deterioration of their vital activity, but they 

 had more or less entirely lost tlieir pathogenous property, in propor- 

 tion to the length of time that the higher temperature had lasted. 

 Exposure for three hours to a temperature of 47^ C. was sufficient 

 entirely to destroy the infectivity, while the appearance of the culture 

 had scarcely changed ; the proliferation of rods and filaments had 

 ceased ; while the development of the rudimentary spores appeared to 

 be rather promoted. 



Fermentation of Bread. f — G. Chicandard thinks that the fer- 

 mentation process by which bread is made does not consist in the 

 hvdration of the starch, followed by an alcoholic fermentation, nor 

 that it is due to a saccharomi/ces ; it consists rather in a transforma- 

 tion of a part of the insoluble albuminoids in the gluten into, first, 

 soluble albuminoids, and then into peptones. The starch is only modi- 

 fied by heating, which gives rise to soluble starch and a little dextrine ; 

 the agent in the fermentative action is a bacterium which is normally 

 developed in the dough ; yeast only accelerates its development. The 

 author discusses the observations and views of previous authoi*s, which 

 he rejects, and gives an account of some experiments on which he 

 has based his own theory. 



Lichenes. 



Morphology and Development of Cladoniaeeae. j — As the result 

 of a careful examination of several species of Cladoniaceas, G. Krabbe 

 comes to the conclusion that this family does not belong exclusively to 

 the fruticose lichens, but that the species must be distiibuted, according 

 to the nature of their thallus, among the fruticose, foliose, and crus- 

 taccous lichens. The classification of the heteromerous lichens into 

 these three families he regards as artificial. The Cladoniacefe consist 

 in fact of genera widely separated from one another, the precise re- 

 lationship of which to one another cannot at present be defined ; but 

 the family cannot be retained with its present limits. The genus 

 Siereocaulon departs widely from Cladonia in its course of develop- 

 ment and in its morphological relationships. 



* O'mptes Rendus, xcvi. (1883) pp. 553, 612. 

 t Il.id.. pp. 61G-7. 



* Ber. Deutbcli. But. Gesellsch., i. (1883) pp. G4-77. 



