[Vor. 8 
14 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
to secretion of enzymes. Many investigators have also shown 
that the formation of enzymes is more or less related to environ- 
mental factors. Although it has not yet been thoroughly 
established to what extent environmental factors are efficient in 
stimulating or retarding the formation of enzymes, brief reviews 
of some of this work should be presented in this connection. 
Katz ('98) studied the regulatory secretion of amylase in 
Aspergillus niger, Penicillium glaucum, etc., and found that the 
effect of various other substances serving together with starch 
as a source of carbon is in general to inhibit the secretion of 
z 
WMillanieters 
P3 
Las 
là, it — /& 9 2 24 ay ab as 
Degrees Centigrade 
Fig. 4. Rate of growth on bean decoction agar. ——— represents Pl and H; 
_—+ P4; - 1; n BY, 
amylase, while the presence of starch alone in the culture medium 
stimulates the fungus to form a large amount of amylase. Her- 
issey (99) studied the appearance of emulsin in Aspergillus niger 
on Raulin's solution and found that the enzyme was observed 
only after 48 hours. If 3 to 4 times as much ammonium nitrate 
as usual were used and this amount replaced at the end of every 
24 hours, such cultures grew for a month without sporulation 
and at the same time yielded no enzyme capable of hydrolyzing 
amygdalin. 
Went (01), in his study of Monilia sitophila, reported that 
at least 10 enzymes were formed by this fungus and he separated 
