939 DISEASES OF INSECTS. 
interlacing and twisting themselves in a hundred different 
ways; so that when confined in the body of an insect, 
from their extreme suppleness and power of contortion 
they find sufficient space wherein to pack their often 
enormous length*. Linné makes one of their habitats 
clay; and Mr. W. S. MacLeay finds them very common 
at Putney in clay at the bottom of pools. 
Dr. Matthey asks—How does the Gordius get into 
Locusta viridissima®? And De Geer—Why do they die 
after having quitted a caterpillar ? and where do they 
perpetuate their species*? These questions, without 
further observations, cannot easily be answered. How- 
ever, it may be supposed that carnivorous insects, such as 
Harpali, &c. may swallow them when found apparently 
dead in clay, where the water has been evaporated, or 
when they have been ejected by other insects; and they 
may revive in their bodies, as Dr. Matthey found them 
to do in water. It is not difficult to conjecture that the 
larvae of Phryganee may meet with them when young in 
the water, and sometimes unluckily swallow them with 
their food. Why they become as dead when they emerge 
from their prey we cannot at present conjecture; but no 
doubt to answer some wise purpose ;—in rainy seasons 
they probably revive and get into little hollows full of 
rain-water. Upon De Geer’s last question—How they 
perpetuate their species—at present I can offer no con- 
jecture. 
@ De Geer ii. 556. ¢. xiv. f. 12, 13. » Ubi supra. 
* De Geer i. 553. 
