New YORK AGRICULTURAL EXPERIMENT STATION. 51 
sults from our use of litmus gelatin did not come up to our ex- 
pectations the progress which has been made in the line of classi- 
fication has been a constant source of encouragement. 
The fact is being recognized that it is its physiological activity 
rather than its ancestry which makes a form distinctive. The 
newer systems of classification tend to emphasize this fact in a 
way that was difficult as long as forms were merely referred to an- 
cestral types. The plan of Fuller & Johnson? and Conn’s* first 
classification aimed to separate the organisms into closely related 
groups. The proper group to which an unknown culture belonged 
having been determined, there remained the problem of establish- 
ing its relation to the small number of related species which com- 
pose the group. The later work of Conn® arranged the germs by 
types, each of which received a name like that formerly applied 
to a species. In the classification now in process of construction 
by the society of American Bacteriologists the aim is to reduce cul- 
tures to physiological groups, each group and its subdivisions to 
be designated numerically in a manner similar to the numbering 
of the books in a library. Whenever convenient, the species name 
may be retained for its appropriate group. 
From what has been said it will be evident that our present re- 
sults must be looked upon as a provisional treatment of the sub- 
ject. It is believed that they mark a step in advance in our knowl- 
edge of the bacteria in cheese, but nothing approaching an ade- 
quate treatment can be expected until the technique is improved 
to the point where a culture can be quickly and accurately assigned 
to its proper place in a satisfactory classification. Then examina- 
tions may be made at sufficiently short intervals to catch the 
various phases of the shifting panorama of germ life in the ripen- 
ing cheese. Until such information is at hand regarding this im- 
portant factor of cheese ripening, attempts at explaining the changes 
which take place in the formation of cheese will be only shrewd 
guesses. 
ACKNOWLEDGMENTS. 
It is a pleasure in this connection to acknowledge tthe assistance 
rendered by Messrs. H. E. Cook, E. L. Jones and G. Merry who 
* Fuller, G. W., and Johnson, Geo. A., Proc. Amer. Pub. Health Asso., 25: 
580-586. 1809. Similar data in Jour. Exp. Med. 4: 609-626. 1899. 
*Conn, H. W. Classification of dairy bacteria. Conn. Agr. Exp. Sta. 
(Storrs) An. Rpt., 12: 13-68. 1899. 
®Conn, H. W., Esten, W. M. and Stocking, W. A. A classification of 
dairy bac‘eria. Conn. Agr. Exp. Sta. (Storrs) An. Rpt., 18: 91-203. 1906. 
