June 9 . 1923 
Treaiing Seed to Destroy Spores 
855 
sulphuric acid was drawn under the cover glass. Immediately the spores 
swelled and became distorted, either bursting at once or else less vio¬ 
lently extruding oil drops and protoplasmic content while the wall soft¬ 
ened and split open. Both content and wall rapidly darkened. Addi¬ 
tion of India ink to the acid made more noticeable the extrusion of even 
small amounts of spore content. After five minutes all the spores in 
the field were obviously collapsed and exploded, or otherwise gave every 
evidence of being killed. The effect of first wetting the spores with 
alcohol was tried, a drop of alcohol being drawn under the cover of a 
dry mount, left about one minute, drawn off, and replaced by acid. In 
this case, the extrusion of the contents and the killing of the spores were 
even more rapid and complete. Water as a wetting agent was less effec¬ 
tive than alcohol. There apparently was no difference between the 
wetting action of 80 to 95 per cent ethyl, methyl, or even denatured 
alcohol, or between the destructive effects of chemically pure or com¬ 
mercial concentrated sulphuric acid. 
Experiments were next made to determine what effect this spore- 
destroying treatment would have on maize seed. Dry seeds of typical 
dent, flint, sweet, pop, and waxy-endosperm varieties of maize were put 
in separate glass jars, covered with concentrated sulphuric acid, and 
stirred occasionally with a glass rod during the 5 to 20 minutes of treat¬ 
ment. The acid was then drained off, and the seed washed for one hour 
in running water. Half of each lot of seed was planted, its germination 
recorded, and the character of the resulting plants observed. The other 
half was carefully dried, and its keeping quality tested by planting ex¬ 
perimental lots from time to time. Although no quantitative results were 
obtained, it was found that even after the most severe treatment the 
viability was retained by a considerable percentage of the seed for as long 
a period as three months, even under the unfavorable rainy season con¬ 
ditions of the Philippines. 
To prevent the persistence of minute air bubbles that might protect 
occasional spores from the acid, similar lots of seed were first given a pre¬ 
liminary wetting with alcohol for about a minute, the alcohol drained off, 
and the acid added. No difference either in immediate wetting effect, 
in subsequent action of acid on the seed, or in ultimate germination of the 
seed was apparent when 80 to 95 per cent ethyl, methyl, or denatured 
alcohol was used. Also there was no apparent difference between the 
effect of chemically pure or commercial concentrated sulphuric acid. As 
a result of the action of the acid, especially after treatments of 15 to 20 
minutes, the surface of the seed became somewhat blackened, but the 
germination percentage was not decreased beyond practicable limits by 
even the longest treatments. Fresh acid was used for each lot of seed 
for fear that the black gelatinous material remaining in the acid might 
dilute it sufficiently to decrease its efficiency. 
Some of these experiments in which representative kinds of maize were 
used are summarized in Table I. Calamba yellow flint is a t^ical exam¬ 
ple of the flinty types grown by the Christian Filipinos quite generally 
throughout the Philippines, Boone County White represents the Ameri¬ 
can dent com that has been introduced and successfully grown on large 
haciendas in several parts of the islands, while Manobo waxy is typical 
of the small, rapidly maturing varieties of maize cultivated by some of 
the non-Christian tribes in the mountains. 
