TIIK ZOOGIXEA OK LEUCONOSTOC MESENTERIOIDES 209 



cells, as shown in Kig. 5 j (which is made up from the drawings in the original 

 treatise, and is here reprod need on account of its historic interest). Since, 

 however, the researches of this French worker were not, performed with pure 

 cultures, we cannot go more closely into the details of tin's illustration. 



It was not until 1891 that a thoroughly satisfactory bacteriological investiga- 

 tion was made by C. LlESENBBRG and \V. /OI-K (I.) on this organism. In the 

 interim, the same gelatinous 

 masses had also been observed 

 in Indian cane-sugar factories 

 by H. WINTER (I.). Adhering 

 to the existing nomenclature, 

 the two first-named workers 

 showed that Leuconostoc mesen- 

 terioides has only one morpho- 

 logical form, viz., a coccus of 

 0.8 to i.o/uin diameter. This 

 discovery in nowise detracts 

 from the accuracy of Cienkow- 

 ski's observations, for it must 

 be remembered that he did 

 not have pure cultures at his 

 disposal, but examined a 

 sample of the gelatinous mass, 

 which from its nature was 

 very likely to have become 

 infected by any number of 

 fission fungi during its re- 

 moval from the sugar-works 

 at Orlovetz to the laboratory 

 of Charkow. 



The discoveries made by 

 Liesenberg and Zopf that this 

 microbe, when grown in or 

 upon nutrient media free from 

 cane- or grape-sugar, does not 



develop a mucinous envelope, but grows in chains, and consequently assumes the 

 streptococcus form (Fig. 55), are entirely new. Such nutrient media are : Solid 

 potato slices, peptonised meat-broth gelatin, milk gelatin, maltose gelatin, on all 

 of which it develops merely a thin pellicle without any formation of mucus ; 

 Liquid milk and bouillon, in which merely a fine sediment of cells is deposited. 

 If, however, a small portion of such a culture of non-mucinous cells be trans- 

 ferred to a medium containing saccharose or dextrose, the formation of mucus 

 quickly ensues. Under these conditions there then develop (on slices of carrot, 

 in particular) large zoogloea, at first dry, like cartilage, but afterwards becom- 

 ing softer and resembling mesentery in appearance. Under the microscope it 

 appears as shown in Fig. 55. The cells, always globular, are invariably arranged 

 in pairs, i.e. as diplococci. The greatly swollen mucinous capsules of the indi- 

 vidual cells gradually coalesce and form agglomerations of constantly increasing 

 size, in which the diplococci are enclosed. Locomotion could not be detected in 

 any case. 



Xot only was Cienkowski's work corrected by the researches of Liesenberg 



and Zopf, but the same fate also befell some of the statements made by Van 



Tieghem. The latter thought he had detected endospores in his Leuconostoc, 



and asserted that in unfavourable media some of the cells increased in size, and 



i o 



FIG. 54. Lenconostoc mosenterioidi-s. 



1-8. Various stages of development of the Zoogloea formation. 

 9. Two chains of cocci, each exhibiting two enlarged (pre- 

 sumably sporogenic) members. Magn. about 500. (After 



