DISEASES OF INSECTS. 239 
How long it can retain this property remains to be as- 
certained. 
De Geer states that he had seen them of the length of 
two feet a ; but they vary considerably in this respect. In 
ants, in which Gould detected them, he states their 
length to be not more than half an inch b . In caterpil- 
lars, which they sometimes infest, they are longer ; in 
that of Notodonta Ziczac, De Geer found one three inches 
and a half long c ; and Rosel three, of six inches, in that of 
Deilephila Euphorbia d ; and in Phalangium cornutum, 
according to Latreille, they extend to more than seven 
inches e . In the larva of a Phryganea L. the author 
first named found one which was more than a foot long, 
corresponding exactly with the Gordius aquaticus of 
Linne ; being forked at one extremity, brown above, 
gray below, and black at each end f . These animals ap- 
pear to die as soon as they leave the body s they have 
preyed upon ; except this happens in water, when their 
activity has no repose. In this element they give their 
bodies every possible inflexion, often tying themselves 
in knots in various places, interlacing and twisting them- 
selves in a hundred different ways; so that when' con- 
fined in the body of an insect, from their extreme sup- 
pleness and power of contortion they find sufficient space 
wherein to pack their often enormous length h . Linne 
makes one of their habitats clay ; and Mr. W. S. Mac- 
Leay finds them very common at Putney in clay at the 
bottom of pools. 
a De Geer ii. 556. " Gould Ants, 63. 
e De Geer i. 551. J Rosel I. iii. 20. 
e Latr. Fourmis, 373. 
• De Geer ii. ubi supr. t. xiv./. 12—14, E Ibid. i. 553. 
h Ibid. ii. 556. t. xiv./ 12, 13. 
