TRANSACTIONS OF SECTION B. 697 
enhance the activity of another. It has long been known that the accumulation 
of the products of metabolism of a cell tend to inhibit the activity of that cell, 
and that if by any means we can destroy or remove the metabolite as it is formed, 
the cell concerned can go on working. Similarly with ferments, and even with 
enzymes, the accumulation of the products gradually inhibits the action as 
Tammann showed in the case of amygdalin and emulsin, and Brown and Morris 
and Lea in the case of starch and diastase, to mention two illustrations only. 
Now suppose we have two organisms A and B living in symbiosis, and 
suppose that A is capable of hydrolysing starch by the excretion of diastase, while 
B removes the product of hydrolysis, by fermenting the sugar as fast as it is 
formed; in this case there is every reason to expect that A will complete its 
hydrolysing action to the utmost, not only because it is of advantage to A to be 
relieved of the inhibiting sugar, but because the diminution of the sugar reacts as 
a stimulus to the secretion of more enzyme. 
There is yet another point to be considered. Katz, in 1898, published some 
results confirming in many points the discoveries of Wortmann, Brown and 
Morris, and others, that fungi, bacteria, embryos, and other enzyme secreting 
organisms not only vary the extent and kind of enzyme secreted, but can be 
stimulated to vary the enzyme according to the quantity or quality of food materials 
at hand, 
I think this line of enquiry may lead to results in the present connection, as it 
is obvious that the products of fermentation of an organism A must be favourable, 
or without effect, or deleterious to the action of another, B, in its immediate neigh- 
bourhood. Moreover, it is shown that a product which is, per se, devoid of either 
favourable or deleterious action, may acquire one or the other if the concentration 
increases. 
Katz regards the action of sugars as not a purely chemical one, but as a 
physiological stimulus; and without pretending to understand the distinction in 
detail, we may admit the importance of the experimental facts, and not only seek 
for, but also hope for, more light. 
Here, then, is a brief sketch of some of the salient features of symbiosis, and of 
some of the physiological factors concerned in the processes ; and though it is far 
from exhaustive, it may serve our purpose to-day of starting a discussion, and of 
showing some lines along which further investigation is desirable. 
Note sur les Fermentations Symbiotiques Industrielles. Par Monsieur le 
Docteur A. Catmerte, Directeur de Institut Pasteur de Lille. 
On sait que beaucoup de champignons inférieurs s’accommodent trés bien de la 
vie en symbiose soit avec des bactéries, soit avec d’autres champignons ou avec des 
algues, soit avec des végétaux ou des animaux supérieurs. On a étudié dans ces 
derniers temps un trés grand nombre d’espéces cryptogamiques parasites. Ces 
espéces parasites ne nous occuperont pas ici. Nous n’envisagerons que l’étude de 
quelques phycomycétes et mycomycétes qui vivent ordinairement en saprophytes sur 
les substances organiques les plus diverses et font subir & celles-ci des transforma- 
tions que homme a pu utiliser pour les besoins de ses industries. 
Les champignons qui nous intéressent surtout sont ceux qui fermentent les 
matiéres hydrocarbonées, telles que la cellulose, l’amidon, les dextrines, les sucres, 
les tannins, ou les matiéres azotées, telles que la caséine du lait. 
Ces champignons agissent sur ces substances au moyen des diastases qu/ils 
sécrétent et qui présentent des propriétés trés voisines de celles que possédent les 
végétaux supérieurs et les animaux, pour l’assimilation des aliments que ceux-ci 
puisent dans le monde extérieur. é; 
Chose trés remarquable, plusieurs de ces étres ont la faculté de produire 
les diastases les plus diverses, suivant la nature des substances qui doivent leur servir 
@aliments. C’est ainsi qu’une des mucédinées les plus vulgaires, le Penicillium 
glaucum, est capable de sécréter tantét de l’amylase, tantét de la sucrase, si on la 
