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is very similar to that given in my former report on potato- -dlisease, (see 
Report for November “and December, 1872, page 010,) in which it is 
shown that two varieties of potatoes, viz, Jackson Whites and Early 
Rose, growing in the same field, and treated alike in all respects, were 
affected differently. The Early Rose potatoes were wholly destroyed by 
fungi, while the Jackson White, although surrounded by the spores of 
the potato-rot fungus, were not affected, 
Having received a supply of seemingly enlthiy potatoes from New 
Mexico, Ohio, and other places, and a tew diseased tubers from Boston 
and Swampscott, Massachusetts, I commenced a series of preliminary 
experiments to test the chemical and structural theories of Dr. Lyon 
Playfair, and the fungoid theories of M. J. Berkeley and other leading 
my cologists. 
In four glass jars I placed a aint of water. In No.1 were placed a 
portion of fungus Peronospora infestans, and the half of an Ohio potato 
remarkable for its healthy appearance. In No. 2 were placed a diseased 
potato containing Peronospora infestans, and the half of a potato received 
from Sante Fé, New Mexico. In No.3 was placed the second half of 
the Ohio potato alluded to, and in No. 4 the second half of the Santa 
Fé specimen. In Nos. 3 and 4 was also put half an ounce of pure sugar, 
to assist fermentation. These specimens were subject, during the ex- 
periments, to a temperature of about 75° F. The respective jars were 
examined from day to day. On the sixth day the Ohio specimen in No. 
1 was found to be rotting rapidly, while the Santa Fé specimen in No. 
2 was apparently uninjured. Specimens Nos. 3 and 4 were undergoing 
slow fermentation. At first the water containing the New Mexican 
specimen became more milky in color than did that of the Ohio specimen, 
a the deterioration on the third day was greater in No. 3 than it was 
in No. 4. 
On the twentieth day the Ohio specimen was perfectly dissolved, form- 
ing a pulp, while the Sante Fé specimen retained its perfect consist- 
ency throughout. On examining the pulp of No. 4 under the microscope 
I found that the starch-granules were arranged in cellulose cells, no lib- 
erated granules appearing on the field of view. Bundles of mycelium and 
budding spores appeared in profusion between the cells. Few infu- 
sorials appeared in view. The odor was slightly sour. The appearance 
of No. 4, as seen under the microscope, of about 80 diameters, was re- 
markable as contrasted with No. 3. The latter specimens presented a 
mass of infusorial life, mycelium, and budding spores. I made many 
examinations of the pulp to detect starch-cells if present, but found 
none. The fermentation had completely destroyed them. The odor was 
very bad. 
The Ohio specimen in No. 1 rotted much quicker under the influence 
of Peronospora infestans than it did under the Torula fungus favored 
by the action of sugar in No. 4 solution. 
The Sante Fé specimen in No. 2 resisted oe Peronospora infestans 
fungus better than it did the Yorula fungus in No. 4; but, by the use 
of either fungus, the tendency of any variety of the ’ potato to resist 
fungus action may, by this modé, be easily decided. Since the preced- 
ing experiments were made, other northern and eastern varieties have 
been tested by fungoid solutions in contrast with some of the New 
Mexican varieties, giving like results, clearly demonstrating the supe- 
riority of the Sante Fé potatoes over all others thus far examined in 
respect to their powers of resisting fungoid and infusorial action. 
It is not unusual to find a decayed spot in the center of potatoes 
otherwise apparently in good condition. A microscopic examination of 
