DISEASES OF INSECTS. 207 
as it would have been if no extraordinary cause had 
prevented it, attached to the hard excrement. He found 
this membrane converted into a jelly occupying great 
part of the stomach, which he conjectured was the proxi- 
mate cause of their death?. 
To conclude this head—spiders are reputed to be sub- 
ject to the stone: I do not say Calculus in Vesica ; but 
we are informed by Lesser that Dr. John Franck hav- 
ing shut up fourteen spiders in a glass with some vale- 
rian root, one of them voided an ash-coloured calculus 
with small black dots®. 
II. I now come to that class of diseases which appears 
to prevail almost universally amongst insects—I mean 
those resulting from the attack of parasitic enemies. 
Thus millions and millions annually perish before they 
have arrived at their perfect state. Diseases of this kind 
proceed either from vegetable or animal parasites. I shall 
begin with the first, which will not occupy us long. 
i. As insects pass often no small portion of their life 
in a state of torpidity, in which they remain chiefly with- 
out motion, it will not seem wonderful, should any par- 
tial moisture accidentally accumulate upon them, that 
it affords a seed plot for certain minute fungi to come up 
and grow in. Persoon observes with regard to his ge- 
nus Jsaria, that one species grows upon the Jarve of in- 
sects (I. truncata), and another upon pupe@ (I. crassa°):— 
as he does not say upon dead larvee and pupe, as upon 
a former occasion‘, perhaps in these cases these plants 
may constitute an insect disease; but I lay no stress 
upon it, and only mention the circumstance here as con- 
* Gwor. ti. 48—-. b-Lesser i. ii. 121. 
© Synops. Meth. Fung. 687. g.63.n.1,2.. 4 Ibid. 4. g. 1. n. 4. 
