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On comparing the freshly-cut surfaces of the healthy and un- 
healthy tubers mentioned, the latter presentefl a mottled and translu- 
cent appearance, while a section of the healthy presented a more uniforni 
color. Itis clearly shown in this case that “ as we sow so shall we reap.” 
On the 12th of April last, a healthy Early Rose potato and a New 
Mexican variety were planted in one of the hot-beds of the Department. 
Over both was placed a glass shade, the object being to produce, by 
artificial means, disease in their foliage. The temperature of their 
_ atmosphere ranged about 68° F. The sand in which the tubers were 
placed was bountifully supplied with water. In consequence of these 
conditions, a very moist atmosphere was kept up in the glass shade. In 
a few days the tubers sprouted—the Early Rose first. The foliage of both 
varieties gradually expanded, but it soon became evident that the leaves 
of the Early Rose, especially the larger ones, had become affected with 
what appeared to be “curl of the leaf.” Upon examination it seemed 
that their upper surfaces expanded more rapidly than their under. The 
leaves of the New Mexican variety became affected similarly, but in a 
less degree. I examined the leaves under a power of about 90 diame- 
ters, but failed to discover any fungoid form. I next ground varicus 
portions of the respective leaves into a pulp, placing portions, thinly 
spread out, under a power of about 300 diameters, but failed 
to find fungoid cells of any kind developed or in progress. Many 
portions, however, of the vascular bundles seemed filled with water in- 
stead of air, a condition which is not usually found, even when leaves 
have been left in water for some time. The under surface of the leaves 
exhibited brown markings, and, when examined with a power of about 
90 diameters, the color was seen to be confined to the outward boundary 
lines of the parenchyma cells of the leaf, showing that the cellular tissue 
was undergoing oxidation. Within a few hours the central parts dropped 
out, and the foliage became riddled with holes. 
Oxidation is not always accompanied by fungus growth. While a 
taper is burning it is undergoing oxidation, but the conditions of change 
in this case render the simultaneous production of fangus cells impossi- 
ble, yet, when fungus cells are undergoing the process of budding, oxi- 
dation of the cellular tissue seems to be necessarily a secondary condition. 
The “ curl of the leaf” may not always be the result of a fungus growth, 
but the conditions which produce it will necessarily retard the growth 
of the plant commensurate to their extent, and pave the way for fungoid 
growths. I next put the plants into separate flower-pots, and exposed 
them to the influences of the open air. Ina few days the foliage of both 
. kinds attained a healthy color, but was stunted in growth. After three 
weeks’ exposure, under favorable conditions as to heat and moisture, the 
foliage of both appeared healthy. 
On June 9, the New Mexican plant put forth flower-buds; while the 
other, although known to be an early variety, did not exhibit any. 
While both plants were passing from their unhealthy condition in the 
open air, many of the leaves of the Early Rose plant wilted and died; the 
leaves of the other remained a healthy green throughout, showing a 
superior vigor. 
On the 19th of May last, three varieties of New Mexican potatoes were 
planted in the Department grounds for experimental purposes, and 
notwithstanding the extreme dryness of the atmosphere during the last 
thirty days their growth has proved highly vigorous. The stalks are 
numerous and from 10 to 12 inches in height. The foliage is abundant, 
has a very healthy appearance, is highly wrinkled, of a dark green color,. 
