1915] 
DAVIS—-ENZYME ACTION IN MARINE ALGAE 821 
THE AMIDASES 
The tissues from the several algae were tested for their 
ability to split NHs from such amino and amido compounds 
as urea, acetamid, asparagin, and methyl amine. These com- 
pounds were used in 1 per cent concentrations. Series were 
set up in which 50 ee. of the substrate to be tested were placed 
in flasks together with 2 grams of the powdered tissue and 
chloroform-thymol as an antiseptic. Checks were used with 
the nitrogen compounds alone and with the algal tissue in 
distilled water. The flasks of duplicate series were kept at 
room temperature and at 35°C. respectively, for 30 days, at 
the end of which time Folin’s method was employed for the 
determination of any NH; that might have been split off. In 
the collection of the NHs, Friedrich’s improved gas washing 
bottles containing 250 cc. of N/50 HCl were used. Air was 
bubbled through by means of a suction pump for two hours, 
then 25 ce. portions of the collection acid were removed and 
titrated against N/50 NaOH, with alizarin red as an indicator. 
In no case was there any action over that evidenced by the 
checks. 
These results are extremely interesting, in the case of Ulva 
especially. This form, as has been shown, thrives in waters 
where the organic nitrogen content is high. The question 
would at once arise whether this increased growth were due 
to the ability of the Ulva to break down the protein molecule 
and thus obtain an increased supply of nitrogen as NHs, or 
whether it were due to the activities of the denitrifying bac- 
teria rendering available a larger assimilable supply. That 
such bacteria are relatively abundant in sewage-contaminated 
water has been shown in the review of literature. We can 
conceive of another factor entering in—that of selective for- 
mation of enzymes. It might well be that with plenty of the 
amino-nitrogen available through the activity of bacteria, no 
amidases would be formed. The possibility of shedding some 
light on this point led to the experiments following. 
Experiments on amidase formation by Chlamydomonas.— 
Chlamydomonas was grown in pure culture upon two differ- 
ent media; one (with one or two modifications, that used by 
