708 SUMMARY OF CURRENT RESEARCHES RELATING TO 



gelatinous envelope, and thick clear cuticle, during which a remarkable 



multiplication of cells takes place, comparable to the formation of auxo- 



spores in diatoms ; (3) the disintegrated condition (status solutus), an 



Aphanocapsa-like condition, into which all the other states may pass. 



The remarkable roughness, or formation of warts and spines on the 



periphery of the cells, is no typical structure, but occurs only in certain 



individuals. 



/3. Schizomycetes. 



Structure and Development of Bacteria.* — Prof. F. Vejdovsky 

 found in a species of Gammarus large numbers of a bacterium which 

 from its size formed a suitable object for examining the structure and 

 development of these minute organisms. The parasite existed in large 

 numbers in the lymph, and also occurred in the fat cells, and sometimes 

 in leucocytes. The single adult rodlet attains a length of 9-10 jx, is 

 2-2*5 /a broad, and its ends are more or less rounded. Many of the 

 rodlets are somewhat narrower about the centre than at the ends, which 

 therefore have a slightly bulbous appearance. A well defined sheath or 

 investing membrane contains a protoplasmic juice and a centrally 

 located nucleus. In the adult forms vacuoles, usually one at each end 

 of the rodlet, are visible, but in the younger forms or germs these are 

 wanting. The young microbe or germ is spheroidal and nucleated, and 

 exists iu the nephridial fat cells as well as in the lymph. The cytoplasm 

 of the fat cells is dilated into cysts distended with young microbes. The 

 smallest germ observed measured 4 /x in diameter. As they grow they 

 lose their spheroidal shape, become elongated and cylindrical, and 

 possessed of vacuoles. The observations were made from films stained 

 with hsematoxylin. and also with magnesia-picrocarmine and contrast- 

 stained with bleu de Lyon. The objects depicted in the fat cells and 

 leucocyte have little resemblance to an ordinary bacterium. Pure cul- 

 tures and infection experiments are not alluded to. 



Influence of Sunlight on Bacteria, f — Herr L. Kedzior records 

 experiments as to the effect of sunlight on bacteria such as B. pyocyaneus, 

 B. diphtherise, B. anthracis, B. typhosus, Vibrio metchniJcovi, and V. choleras. 

 Sunlight exerts a bactericidal action, not only in the presence of oxygen, 

 but also, though to a less extent, in that of hydrogen. The latter is 

 also less marked if the bacteria be suspended in some fluid. After four 

 hours' exposure to sunlight the cholera vibrio became quite harmless, 

 though after two hours it remained sufficiently virulent, when injected 

 intraperitoneally, to kill animals. On garden earth and on drain and 

 sewage water the' action of sunlight is but feeble. The colour of the 

 soil exerts inhibitory influences of variable intensity, for while the 

 chemical rays take 15 minutes to penetrate a layer of garden mould 

 2 mm. thick, they pass through a layer of sand of equal thickness in 

 5 minutes. After their transit, their bactericidal action is lost. 



Flocculation of Bacteria.^: — Mr. K. Greig Smith records some 

 interesting observations and experiments on the effect of certain salts 

 on bacterial suspensions. From his experiments he infers that bacteria 



* Contralbl. Bakt. u. Par., 2 te Abt., vi. (1900) pp. 577-89 (1 pi.). 

 t Arch. f. Hygiene, xxvi. (1899) p. 323. See Bot. Centralbl., lxxxiii. (1900) 

 p. 240. t Proc. Linn. Soc. N. S. Wales, xxv. (1900) pp. 65-7. 



