98 CLASSIFICATION AND DESCRIPTION OF BACTERIA 
2. Those bacteria which require organic carbon but are able to dis- 
pense with organic nitrogen. These forms utilize sugars, nitrogen, 
ammonia or nitrates. 
3. Those forms which require both organic nitrogen and carbon. 
Inorganic substances are of little use. 
Jensen attempted to devise a system which would show the rela- 
tionship of forms. Reasoning from the synthetic processes, he con- 
structed a family tree for bacteria. His methanomonas is proposed 
as the first bacterium on earth and he considered it the beginning of all 
life. The method of nomenclature in this system is cumbersome and 
so far his proposals have been of little more than theoretical interest. 
The present-day system and those which are developed in the 
future must rest upon the past work in this field. Fischer, in his book 
previously referred to, has stated that the very factor contributing 
to the progress of bacteriology, the number and variety of its students, 
has been a great hindrance. There are pathologists, chemists, brewers, 
botanists, all of whom are making species or varieties. Fischer does not 
claim that to any one class of investigators should be given the priv- 
ilege of systematizing the science, but that established principles 
should be followed. 
A student reviewing the systems which have been proposed for the 
classification of bacteria realizes that the problem is a difficult one. 
The number of systems which have been proposed supports this state- 
ment. Smith has said that no harm will come to anyone if all of these 
perplexing questions are not settled definitely within his own 
generation. 
The Society of American Bacteriologists has been wrestling with 
the classification of bacteria for some little time. The Committee 
(Winslow, 1917) has made an interesting report in which the more 
important classifications of the past have been discussed. This com- 
mittee has proposed the following eight families: 
Family 1. Nitrobacteriacesz. 
Family 2. Mycobacteriaces. 
Family 3. Pseudomonadaces. 
Family 4. Spirillacese. 
Family 5. Coccaces. 
Family 6. Bacteriacez. 
Family 7. Lactobacillaces. 
Family 8. Bacillacese. 
The classification will probably demand much more study before a 
