466 
Journal of Agricultural Research 
Vol. XXVII, No. 7 
Hence, it is possible that entirely new relationships may occur within 
the protoplasmic cell contents as a result of the action of some substance— 
e. g., benzaldehyde, certain organic acids, ketones, or alcohols—even 
though the possibility of this action may not always be indicated by a 
specific change in the surface tension of the solution. 
Price (39) has made observations on the protoplasmic condition of 
certain fungous spores. He used the method of dark ground illumina¬ 
tion in studies on dormant and germinating spores of Mucor sp., Melamp - 
sora rostrupii Wagner, Triphragmium ulmariae (Schm.) Link, and 
Phragmidium disciflorum James, and has adduced further evidence on 
the colloidal nature of the plasmic contents of these bodies. He 
is of the opinion that the entire spore content is protoplasmic and of 
the nature of an emulsoid colloid. In the dormant spore the protoplasm 
is gellike, and at germination the most important change is the trans¬ 
formation from the gel state to a hydrosol. 
It would appear, from the fact that so many substances stimulate the 
germination of spores of Urocystis tritici , that their action is such as to 
change the physical condition of the spore contents, facilitating a change 
of phase similar to that observed by Price and thus finally increasing the 
permeability of the spore contents. 
Only small quantities of the stimulating materials were necessary, 
but it is possible, even in the high dilutions observed, that, owing to 
their physical properties, they readily concentrated at the surfaces and 
that there may have been a quantitative relationship between the actual 
amount of the substance in solution and the number of spores which 
responded to the action of the stimulus. This, however, was not apparent 
in the dilution tests. 
It has been pointed out that the spores of Urocystis tritici ordinarily 
germinate slowly. Without the intervention of a stimulus, the spores 
may require up to 16 days at 20° C. before they germinate. The first 
stage of germination is generally considered to be the imbibition 
of water. The relatively impermeable spore wall permits the ingress 
of water only very slowly, but when the permeability of both spore wall 
and spore contents is increased, the spores germinate within a few hours. 
If the evidence justifies us in considering that the stimulatory sub¬ 
stances probably cause a physical change of state in the protoplasmic 
cell contents and thus increase permeability, we might expect that this 
action probably is not specific for U . tritici. The spores of other fungi 
which do not germinate readily in water, or which seem to require a 
rest period before germinating, might also be stimulated by the same 
substances. 
Preliminary tests were made with the spores of Urocystis occulta , 
Colletotrichum lindemuthianum , and the teliospores of Puccinia graminis . 
Evidence was obtained that they also respond to such treatment. Such 
results indicate that caution is necessary in concluding that definite rest 
or maturation periods are necessary for the spores of such organisms, 
without taking into consideration the nature of the environmental condi¬ 
tions to which the spores have been subjected. 
The methods used in the studies of spore germination in Urocystis tritici , 
which involve the use of surface films or highly diluted solutions of stimu¬ 
latory substances, would appear to indicate a fruitful mode of attack in 
studies on the germination of other forms. The practical importance of 
the method in its relation to pathogenicity studies with certain other 
fungous spores requires no further comment. 
