1900] CHROMOGENIC BACTERIA 393 
possibly be acetic acid, since it has been possibleto isolate alcohol 
and acetic acid from some cultures, yet this is by no means cer- 
tain, since it is not clear whether these compounds existed pre- 
formed, or were the result of changes brought about by the 
analytical methods employed. 
In the light of much experimental evidence extending over 
a considerable period of time, there seems to be no other 
hypothesis tenable than that all the different colors produced are 
simple derivatives of one and the same substance, that is to say, 
the organism does not produce different pigments on different 
media, as was first supposed, and as has been stated of many 
other chromogens. 
The reactions and properties of this pigment do not corres- 
pond to those given by other investigators who have worked 
upon coloring matters of similar colors. The greens cannot be 
chlorophyll, nor can the blues be any one of the many cyanins 
which have been described. The pigment most closely resembles 
the coloring matters which have been isolated from lichens and 
from fungi, yet this resemblance is but slight. 
The writers hope in a future communication to be able to 
announce something definite as to the nature of the pigment, and 
_ whether it belongs in reality, as now seems to be the case, toa 
new class of coloring matters heretofore unreported among the 
pigments of chromogenic bacteria. 
One of the chief difficulties is to obtain sufficient purified 
pigment, for although its tinctorial power is very great there is 
but little of the material formed in each culture, and much of 
this is necessarily lost in the processes of purification. The prob- 
lem becomes, therefore, in the first place, one of time, and 
- cultivation of the organism on a large scale. 
LABORATOIRE p’ HYGIENE, 
CHEMICAL L 
ABORATORY 
tes Université de Nancy. France. 
Cornell University. 
