18 Proceedings of the Royal Iris/i Academy. 
efficient way of eradicating the potato disease would seem to be one 
identical with that adopted for putting an end to the "rinderpest" in 
cattle, and which has received the name of the " stamping-out pro- 
cess." On inquiry, a cultivator informed me that it was believed that 
some slight advantage had been gained by burying the potato plants 
first infected. But, whilst this is encouraging, it is now plain that, for 
any " stamping-out process" to have a reasonable chance of success, it 
should be conducted carefully and generall}^ Unless the utmost care 
be used, the uprooting of a plant to bury it will shake off innumerable 
spores, to be blown away as contagion; and such care would not 
be thought of until it was taught that the disease was contagious, and 
that the contagion consisted of this minute fungus. Again, the anxious 
labour of one cultivator would be quite wasted, unless the rule were 
general; for his carefully manipulated field might receive a new shower 
of spores, with any turn of the wind, from fields which had been 
neglected. 
If, therefore, it be desired to make a real attempt to extirpate 
a pest, which has caused, and may again cause, excessive misery and 
immense loss, the same earnest system of compensation, penalties, and 
scientific inspection should be adopted to eradicate the potato disease, 
as was employed successfully to annihilate the rinderpest. 
Figs. 14, 15, and 16, are representations of crystals. Some of them 
represent raphides, and probably are the raphides of cells liberated 
from bruised, broken, or half-masticated plants. Others, such as fig. 16, 
appear to be crystals of hippuric acid, caught up by the winds from 
places which had received the excretions of herbivores. 
Fig. 17 is the pectinate antenna of one of the Lanpyridse. 
Fig. 18 is a moth-scale of a remarkably beautiful form. Both 
scale and antenna were possibly lost in some struggle between their 
possessors and a piratical wasp in the air. 
Figs. 19 and 20 show a number of objects, more or less contorted, 
chiefly remarkable for having a great number of hair-like processes. 
It was impossible to tell, with certainty, from what source they were 
derived. One resembled the spermatozoid of a fern, but the remainder 
appeared to be fragments of exuviae of minute animals. The hair-like 
processes, like cilia, were found fine and semi-transparent. 
Fig. 21, apparently a larva, on being measured with the micrometer, 
was found to be j^^th of an inch in length. 
Fig. 22 is an acarus, magnified with 1 inch object-glass. This mem- 
ber of the Arachnida class was found in the air over heathery hills, at 
breathing level. It will be recollected that Pouchet found an arach- 
nide-larva in one of the air-passages of the human lungs. 
Considered from a medical point of view, I may remark that, whilst 
some of these objects might affect the lungs injuriously by mechanical 
occlusion, obstruction, or irritation of the finer air-pipes, some might 
influence them in another way. On the one hand, the dust, pollen, crys- 
tals, moth-scales, antenna, and the like, might — if they were not, as 
fortunately they are, few in number — tend to produce embolic phthisis. 
