1914] HOYT—COLLOIDAL METALS 209 
above described, produced in alkaline solutions of colloidal metals, 
may be considered as catalytic phenomena due to the colloids, the 
latter acting in a manner more or less similar to that in which the 
organic colloidal catalytes which we term enzymes are known to 
operate; if catalysis results frequently from enormously extended 
surfaces, it may not be without the bounds of probability to suppose 
that alterations in organic material, similar to those produced by 
the organic enzymes, may be brought about by inorganic colloids 
such as those dealt with in the present paper. It seems also pos- 
sible to relate the swollen cell walls observed by Kies, in the 
study above discussed, to some catalytic action which has altered 
the water-imbibing power of the wall material, rather than directly 
to the forces which are active in producing absorption and forma- 
tion of his precipitates. To attempt the extension of this general 
hypothesis to the details of the various instances would be out of 
Place at the present time. 
It is worthy of note that the swellings with which this paper has 
had to do were most pronounced in Spirogyra decimina, less so in 
S. longata from the stock culture, and were not exhibited at all by 
the latter form from the culture in Crone’s solution. That the last 
mentioned material was the most vigorous, while the stock material 
of S. longata was next in order, and the material of S. decimina was 
apparently least healthy, suggests that the portion of the cell wall 
taking part in the swelling differed in the three sorts of filaments; 
Susceptibility to the swelling influence exerted by the colloidal 
metals seems to have been greater as the alga was less vigorous. 
Whatever may have been its explanation, we have here another 
‘xample illustrating the fact that similar filaments of the same algal 
Species, but cultivated under different conditions, may be expected 
to Attain different physiological states, thus becoming physio- 
logically quite dissimilar. Such differences are apparently indicated 
in the present instance by the diversity above noted in the suscep- 
tibility of the outer portions of the cell walls in the three kinds of 
algal material. The existence of different physiological states in 
Individuals of a single species is of course well known to all experi- 
menters. It has been previously shown for Spirogyra, by the 
Present writer (8), by parallel and exactly similar experiments 
