54 BOTANICAL GAZETTE [JANUARY 
bacteria, amoebae, flagellates,etc. Busgen*? found that Botrytis 
reacts to surface tension by the formation of little bundles of 
branches perpendicular to the touched surface. 
Besides the previously mentioned contact experiments, 
recourse was also had to the clinostat. By shaking, spores 
were submerged in flasks containing a small amount of distilled 
water. These flasks were then rotated horizontally so that there 
was constant movement of the spores and considerable contact 
with the glass surface. The results were negative. Likewise 
experiments made with a shock-imparting clinostat, and also with 
a combination of the rotation and shock, failed to give any posi- 
tive results. 
A small number of experiments was made to test the effect 
of evaporation caused by a lowering of the vapor tension. To 
effect this the cells were arranged in the Petri dishes as before. 
Water was used in the hanging drop above, except in control 
experiments, and below was placed the salt solution of various 
strengths. Over solutions of MgSO,, varying in strength from 
$n to 3n, by far the best germination occurred over $x. where 
drying out was quite gradual. 
According to Lesage,** who made a number of experiments 
to determine the dampness of the air in which spores would 
germinate best, the spores of Penicillium germinate well at all 
of the higher densities, but reached the lower limit between 82 and 
84 per cent. humidity. Aspergillus germinates so well ordinarily 
at the higher humidities that the factor of evaporation seems of 
more significance. 
The action of a change of concentration of the medium was 
tested in a small way. Spores of Aspergillus flavus were sown 
in Erlenmeyer flasks containing respectively 20, 10, and 5 per 
cent. KNO, in one series, and in another the same strengths of 
MgSO,. After twenty-four hours about 5 to 10 per cent. of 
germination had occurred in the KNO, cultures and about 10 
‘7 BUSGEN, M.: Ueber einige Eigenschaften der Keimlinge parasitischer Pilze. 
Bot. Zeit. 51 : 53-72. 1893. 
**LesaGeE, P.: Recherches expérimentales sur la germination des spores du 
Penicillium glaucum. Ann. d. sci. nat. Bot. 8: 309-322. 1895. 

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