254 SUMMAKY OF CUKEENT RESEARCHES RELATING TO 



oflF, and then finally separating from one another. In these cells 

 i"epeated bipartitions take place, even before they become isolated, 

 colonies of cells being thus formed, which attain a zoogloea-character 

 from the gelatinizing of the cell-walls. These zoogloea-cells 

 develope into unicellular or bicellular rods. 



A Schizomycete to which the author gives the name Bacterium 

 merismoj^oediodes occurs in the form of colourless cocci which do not 

 develope into rods. The cocci form rectangular more or less regular 

 unilamellar colonies, the number of cells being always a power of two, 

 which may amount to 64 x 64 ; and a number of colonies may coalesce 

 from the disappearance of their enveloping membranes. Finally, 

 when the substratum is exhausted, the cells separate themselves from 

 their combination, and become motile. These develope into long 

 filaments, which divide up into rods and finally into cocci ; and the 

 cocci, when isolated, are again motile and form merismopoedia- 

 colonies. 



In another publication,* the same author adduces further evidence 

 that all the genera of Schizomycetes described by Cohn and others 

 as distinct, viz. Micrococcus, Bacterium, Bacillus, Lepiothrix, Clado- 

 thrix, Vibrio, Spirillum, Spirochcete, Ophidomonas, Monas, &c., are 

 simply different stages of development. This applies even to the 

 spiral forms, Vibrio and others, with respect to which it had not pre- 

 viously been suggested. The various forms of development are, as 

 in the higher fungi, dejiendent on conditions of nutrition. 



A special description follows of the following peculiar forms : — 

 Cladothrix dichotoma, Beggiatoa alba and roseo-persicina, and Creno- 

 thrix Kuhniana. 



Microphytes of Caries of the Teeth.f— W. Miller states that an 

 examination of the microphytes which accompany caries of the human 

 teeth does not confirm Koch's view that the coccus- bacillus- and 

 spiral forms of pathogenous schizomycetes are morphologically 

 constant and genetically distinct. The Leptofhrix buccalis occurs in 

 all three forms. The entrance of this schizomycete into the tooth is 

 preceded by a disappearance of the lime from the enamel and dentine, 

 occasioned by acids formed in the mouth. Miller asserts the remark- 

 able fact that a saccharomycete {Saccharomyces 3Ii/coderma ?) some- 

 times perforates the enamel of sound teeth, making way for the 

 entrance of the Leptothrix. 



The first stage in caries of the teeth, the removal of lime from the 

 tissue, is caused principally by acids produced by fermentation in the 

 mouth. The enamel then gradually disappears, while of the dentine 

 a porous mass remains, which afibrds entrance to abundance of Lepto- 

 thrix in the bacillus and micrococcus form. The filaments of 

 Leptothrix occur only on the surface or in the upper much-decayed 

 layers, and appear to take but little part in this invasion. The 

 bacilli, on the other hand, penetrate deeply, even into the finest ramifi- 



* Zopf, W., ' Zur Morphologic der Spaltpflanzen.' Leipzig, 1882 (1 pi.). See 

 Bot. Centralbl., xii. (1882) p. 217. 



t Arcliiv fiir experiment. Pathol, u. Pliarmakol., xvi. (1882). Sre Bot. 

 Centralbl., xii. (1882) p. 231. 



