1922] HELLER—ANAEROBIC BACTERIA 73 
single species for which the cultures were named. Unfortunately 
the anaerobe strains of some of our own institutions are but little 
better. 
It would be difficult for the systematist employed in the study 
of higher plants whose major characters are well understood, whose 
mutations are today being scientifically studied, whose formal 
structure of classification was laid down many years ago and has 
been systematically developed, to imagine the complexity of the 
problem confronting one desirous of bringing order into the chaos 
represented not only by this war literature, but also by thirty 
years of anaerobic literature written before it. The time is more 
than ripe for some organization to enable new students to set to 
work with some clearness and assurance, an organization with a 
Synopsis or index to the enormous literature that they must consult. 
This should give them an idea of the multiplicity of the species 
they will encounter, and should consider the biological factors 
relating to morphology, chemical behavior, and mutation as they 
are understood today. 
Several workers have stated that anaerobic bacilli do not mutate. 
This is their natural reaction in denying the existence of the type 
of mutation that was described by the workers with impure cultures. - 
To state that a living strain does not mutate would be to claim that 
it lacks one of the best recognized attributes of living matter. 
Obviously, it is necessary to determine where the mutations of 
bacteria lie, and what range of possible change they cover, before 
one can tell what characters are stable enough to be used for 
systematic purposes. The enzymes of the anaerobic bacilli are 
among the most highly active chemical agents known. Some of 
the anaerobes will be found among. the most active splitters of 
carbohydrates, others have almost unbelievable proteolytic powers. 
It is to be expected that mutations will frequently be encountered 
in highly specialized organisms of this sort, and that these mutations 
will be chemical in their nature. When a mutation occurs that 
enables the organism to render assimilable a substance that its 
parent was unable to utilize, the mutant is readily detected because 
of the larger colony that it produces. Likewise a bacillus that loses 
a metabolic power forms smaller colonies than its parents. Data 
