( 646 ) 
tap-water with 2 pCt of glucose, 0.5 pCt of asparagine, 0,02 pCt 
K,HP0 4 , always cultivated at 30° C. and with repeated transports after 
two days or longer. From this we also recognise that there is no 
question of a direct influence of the food on the production of the variant. J 
The auratus- and hyalinus-v ariants, also, have only taken rise in liquid 
cultures, namely in broth and ip the glucose-asparagine solution. 
Moreover, hyalinus, which is of a deep vine red, is easily obtained 
from a solution of pure gelatin in tap-water with 0.02 pCt. K 2 HP0 4 , 
after repeated re-inoculations, at 30° C., whereby also hyalinus 
viseosus results. 
The colourless or white variants, which only differ from the original 
form in producing no pigment, should certainly be considered as | 
minus-variants. They are obtained with more ease than the slime 
variants and, at least as to N° 4, have also been detected by other 
authors 1 ). 
Except under the said conditions, apt to keep them constant, all • 
the cultures as well in liquid as on solid media, vary sooner or 
later towards white. The original form does remain preserved, but 
a colourless variant is thrown off, which is still more constant than 
the stock itself. 
Not always does one and the 6aine variant result in this case: 
two uncoloured constant forms, N° 4 and 5 can easily be distinguished 
if they originate at the same time, and their colonies are on the same 
agarplate so that they may be compared somewhat magnified. 
One, albus hyalinus, then looks more blueish transparent, the other, 
alhus, is more of a cloudy and opake white; under the microscope 
the former proves to consist of smaller cells than the latter. 
The cause of the production of white variants cannot be a more 
or less abundant access of oxygen, but must probably be sought in 
a stimulus, exerted by secretion products which remain enclosed in 
the interior of the cells. 
Although the presence of ammoniumcarbonate in the medium 
(broth-agar), as also cultivation at temperatures higher than 30° C. 
e.g. at 33° C., prevent pigment production, no hereditary variation 
at all is caused by these influences. If the thus treated colourless 
cultures are transported at 20° to 25°, no white variants are obtained 
from them, but the normal fonq is found back unchanged, if at 
least the above mentioned precautions to preserve the constancy of 
the stock are not neglected. 
') In Lehi 
coloured im 
mann and Neumann’s Atlas, 4‘»« Ed. 1907, Table 30, Fig. 3, shows 
sage of a “pure culture” of prodigmus, consisting of red and white 
