1897.) Vegetable Physiology. 229 
long time, and often multiplied enormously in the beet juice, forming 
cart-loads of the so-called “frog spawn.” In 1878 van Tieghem also 
studied the organism (Ann. d. Sci. Nat. Bot. Sé. 6. t. 7. p. 180),considered 
it to be closely related to Nostoc, and renamed it Leuconostoc mesen- 
teroides. His observations contradicted those of Cienkowski in several 
important particulars. He found no rod-shaped bodies, but only a coc- 
cus, which, in exhausted material converted some of its members into 
spores, particular cells of the chain enlarging perceptibly, becoming 
more refractive, and taking on a thicker wall. His first material was 
discovered in the laboratory by accident in macerations of dates and 
carrots. Subsequently the organism thus found was compared with that 
from the beet sugar vats and found to be identical. In 1892, Liesenberg 
and Zopf published two papers which threw a flood of light on the sub- 
ject (Zopf: Beiträge I and II). They first obtained the organism from 
the Spree River water, below certain breweries, starch factories, etc. 
This form was subsequently compared with material from a beet sugar 
factory in Germany, and found to beidentical. Their experiments coy- 
ered a period of two years, and were carried along in two parallel series 
(1) with the European organism and (2) with material obtained from 
cane sugar vats in Java. The Javan and European form proved to be 
morphologically identical, and there were only a few very slight physio- 
logical differences, The organism as it comes from the vats is always con- 
taminated with other bacteria, which stick to the gelatinous sheath. 
Pure cultures were therefore obtained with some difficulty, and only 
after it was discovered that the contaminating bacteria could be de- 
stroyed by heat without injury to the Leuconostoc. Poured plates 
made after exposing the finely rubbed mass in fluid to 75° C. for 15 
minutes invariably yielded an abundance of pure colonies. The organ- 
ism is plainly dimorphic. In solid or fluid nutrient media containing 
grape or cane sugar it multiplied in the ordinary gelatinous or cartila- 
ginous, lumpy, frog spawn form. In similar media destitute of grape 
or cane sugar it grew in an entirely different form, i. e., as an erdinary, 
thin-walled Streptococcus. The two forms were So remarkably differ- 
ent both macroscopically and microscopically that the Streptococcus 
form was at first supposed to be some intruding organism ; but repeated 
transfers of the two forms back and forth always gave the same results, 
i. e., the frog spawn form on nutrient media containing sugar, and the 
nude form on the same media when free from cane or grape sugar. 
The change from the nude to the covered form was followed in 
hanging drop cultures, and occurred in 12 to 24 hours. In nature the 
organism probably most often occurs in a form quite unlike that found 
