
56 BOTANICAL GAZETTE [JANUARY 
The poorest results were secured when the fresh spores were 
directly sown at the room temperature. Cooling also had a 
favorable influence upon the uredospores. This excessive cool- 
ing is hardly a natural stimulus. It may be regarded perhaps 
as a substitution stimulus, able effectually to. replace some other 
incitation of the natural environment. 
A few experiments were made with reduced oxygen supply, 
mainly to see if slight variations in this regard would at all 
vary the results. With cultures at room temperature with an 
air pressure of 60™™ there was no noticeable effect on germina- 
tion, either in water or in nutrient solution. At below 40™™ of 
air pressure there was marked retardation, but since such lower 
pressures were of little concern in these results, the matter was 
not carried farther. 
INHIBITION OF GERMINATION BY NUTRIENT SOLUTIONS. 
Various authors have made casual reference to the fact that 
ordinary nutrient solutions may injure the germination of certain 
fungi normally germinating in water alone. A thorough study 
of this matter should throw some light upon the conditions 
necessary for the penetration of the host plant by the parasite. 
As yet I have had opportunity to make but few experiments in 
this direction, but an accidental attempt to make a substitute 
for bean decoction by adding peptone to the standard nutrient 
salt solution gave some results of interest with certain smuts 
used. Ustilago Avenae and U. perennans gave but a small per 
cent. of germination on any solution containing 1 per cent. of 
a German preparation of peptone; and the pure peptone solu- 
tion gave only 1 or 2 per cent. of germination. An American 
manufacture of peptone did not act as an inhibiting agent; but 
the pure peptone solution afforded no better germination than 
distilled water. On the other hand, Ustilago was not inhibited 
by either preparation of peptone. 
Certain rust fungi also comport themselves sornewbial pecul- 
iarly towards nutrient solutions, as seen in Table VI. 

