MICHIGAN ACADEMY OF SCIENCE. 
61 
of HC1, in quantities of 25cc, n/16384 (Dandeno, Am. Jour. Sci., 17 June, 
1904, p. 455. y, but die in a solution of n/8192. Lupines are about the same. 
For CuS0 4f corn just lives in a concentration of n/524288, and dies at the 
next stronger concentration. Lupines are more resistant than corn to C 11 SO 4 , 
Lupines (the radicles) can survive a concentration (25cc) of n/65536, but 
die in the next stronger. If we arrange the three fungi Ustilago, Macros- 
porium , and Glomerella with corn, lupine and pea radicles to show the relative 
resisting power ( 1 ) against HC1 we get: Ustilago , 1024, Macrosporium 256, 
Glomerella 128, corn 2 , lupine 1, pea 1. This means that Ustilago resists 
a solution of HC1 1024 times as concentrated as the lupine or the pea. ( 2 ) 
With regard to C 11 SO 4 , the following figures appear. Ustilago 1024, Macros- 
porium 1024, Glomerella 256, lupine 8 , pea 2 , corn 1 . The figures for corn, 
lupines and pea are taken from a table on page 455 in the paper already 
cited (Am. Jour. Sci. 1904.) 
The cells of the radicles of the seed plants just mentioned are probably 
not very different from living cells of the mesophyl of the leaves, so that 
when the problem of spraying is under consideration, it should not be for- 
gotten that the fungus which it is desirable to destroy, is much more, very 
much more, resistant than the living, sub-epidermal cells of the leaves. 
But the cutin, trichomes, wax, oil or other substance on the surfaces of 
leaves, protect the living cells within the leaves, so that it is possible to use 
a spray liquor sufficiently toxic to destroy the fungus, and yet not seriously 
injure the leaf. 
In preparing and examining the numerous slides required in the experi- 
ment, it was found that small particles of dust, or of other matter which 
might be deposited on the slide with the spores to be tested, affected often 
quite seriously the solution. The spores which happened to be within the 
neighborhood of such foreign particles, or clusters of particles, survived 
the solution, while others on the same slide did not. These substances 
simply reduced the toxic action, by physical affinity, of the solution. But 
this is not surprising in view of the experiment of Ruby Fitch (Annales 
Mycologici IV, 4, 1906), who showed that sand, glass, broken pottery and 
other substances reduced very materially, under certain conditions, the 
toxic activity of the solution. 
Similar results were obtained by the writer ( 1 . c.) with radicles of corn, 
pea and lupine. It was found in those experiments that pure sand, when 
added to the toxic solution, reduced the toxic activity in some cases as 
much as 128 times. This means that, when sand is present, 128 times as 
much C 11 SO 4 might also be present without any further injurious effect. 
From these experiments, two points of some importance in laboratory 
work were made. (1) Corn smut does not germinate very readily until 
January or February following the harvesting of the corn crop. The brand 
spores seem to require a resting period. ( 2 ) Hydrochloric acid, about n /128, 
or copper sulfate, n /2048, furnish excellent media in which to produce spor- 
idia from the brand spores. In these liquids, the spores germinate much 
better than in tap water, distilled water, or manure decoction. Moreover, 
HC1, and CuS0 4 , on account of their toxic action, check the growth of an 
enormous number of things which would be likely to appear in water or 
manure liquor. They act as a sort of a medicine to the preparation. 
The experiment with KOH and NaOH did not show any result which 
seemed of very great importance. KOH is undoubtedly more toxic than 
NaOH. The same is true with radicles of pea and of lupine. If these be ar- 
ranged with the fungi in order of resisting power against KOH (25 cc.) we 
