540 
IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
is a term applied mainly to processes involving the formation of 
alcohol, though it has lately come to be used in a much broader 
sense. Putrefaction may be defined as that process of disinte- 
gration which results in the formation of poisonous products, 
as the so-called ptomaines, and products with offensive odors, 
such as the organic sulphur compounds and the indol derivatives. 
In general, fermentation is usually ascribed to yeast and putre- 
faction to anaerobic bacteria. In fermentation the part played 
by amino acids is more or less incidental, the main reaction hav- 
ing to do with the breaking down of carbohydrate. Putrefac- 
tion on the other hand, has to do directly with amino acids, 
and the disintegration of the latter may be retarded or even 
prevented by the presence of carbohydrate. 
Ackerman has proposed the term aporrhegmata to designate 
all those fragments of amino acids which can be formed from 
the latter by the vital functions of animals and plants. Many 
of these products have been determined in an experimental 
way, by adding an amino acid of known purity to a culture 
medium, inoculating with the desired organism, and after a 
sufficient time of incubation identifying the products. Prom 
such experiments a large number of data have already been 
secured, but as yet no attempt has been made to assemble and 
correlate them, with a view to determining the fundamental 
nature of the process. 
The following table was constructed by the writer after a 
careful search of the literature. It is based mainly upon the 
work of Ehrlich, Effront, Drechsel, Neuberg, Pringsheim and 
Ackermann. 
