479 BOTANICAL GAZETTE [JUNE 
1/1,000,000 mol. repels, while it requires a somewhat stronger solution of hydro- 
chloric acid to attract, and 1/600 mol. of the latter is the optimum for attraction. 
In acids the attraction is parallel to the dissociability. In high concentrations acids 
repel, due in strong mineral acids to the excess of hydrogen ions, and in weak organic 
acids to the undissociated molecules. In many of the latter acids the strong 
attraction of the hydrogen ion and weak repulsion of the molecule leads to injury 
and death of the spores because of the toxicity of the latter. The reaction, both 
negative and positive, is ““apobatic” (PFEFFER’s terminology) or involves “motor 
reflex” (JENNINGS). JENNINGS maintains that all tactic responses in animals are 
of this type, and that PrerFEr’s so-called “‘strophic”’ reactions do not appear. He 
thinks it likely also that the same is the case in plants, and KusANno’s work brings 
more evidence for the support of this probable contention WILLIAM CROCKER. 
Germination of spores of rusts.—In a paper by SCHAFFNIT?' some observa- 
tions and experiments are given which seem to throw some light on the questions 
relating to the germination of uredospores and aecidiospores of the rusts. The 
irregularity of germination of these spores is well known to all experimenters, but 
no satisfactory explanation for their behavior has been given. ScHAFFNIT finds 
that the capacity for germination depends largely upon the degree of maturity 
of the spores. By mature spores he understands only those which have fallen 
from their stalks without being shaken by air currents or rain. Ordinarily large 
numbers of spores fall from the sori on account of the motion of the infected 
leaves, caused by the wind. The majority of these spores do not germinate, but 
if spores are gathered on a hot quiet day, when there is no wind, 80-100 per cent 
germinate within two hours. The thoroughly ripened spores have a darker 
color than the immature ones. Spores which have been separated prematurely 
from their pedicels are incapable of being ripened afterward. It seems, also, 
that spores cannot be ripened on leaves that have been cut from the plants. 
ese observations suggest an interesting field for further investigation in the 
ecology of fungi. It must be confessed that our knowledge of the actual behavior, 
means of distribution, and germination of fungus spores in nature is very meager, 
even as to fungi of economic importance. Any contribution to this subject is 
important. The wide application of these results, which the author makes, 
would hardly seem justifiable until more extended and more accurate experiments 
have been conducted.—H. HAssELBRING. 
Color production in Penicillium.—The effect of external factors on the color 
production of a certain species of Penicillium has been investigated by DorEBELT.”’ 
It seems that in agar cultures the pigment, which is red, appears first near the 
2t SCHAFFNIT, ERNST, Biologische Beobachtungen iiber die Keimfahigkeit und 
Keimung der Uredo- und Aecidiensporen der Getreideroste. Ann. Myc. '7°599-523- 
1909 ; 
22 DoEBELT, H., Beitrage zur Kenntnis eines pigmentbildenden Penicilliums. 
Ann. Myc. '7:315-338. 1909. 
