16 
ARCANA ENTOMOLOGICA. 
worms, which, it has been maintained, feed exclusively on milky- 
juiced and caoutchouc-yielding plants. Such at least seems to be 
the legitimate inference from the extensive generalization of Dr. 
Hoyle, whose statement is as follows :— 44 In a paper read to the 
British Association at Bristol on the plants which yielded caoutchouc, 
I observed that they all belonged to the milky-juice families of 
Chicoraceae, Lobeliacese, Apocynacese, Asclepiadacese, Euphor- 
biaceae, and Artocarpem, a tribe of Urticacese. In the first place, 
it may be observed that many of the plants of these families are 
remarkable for the strength and tenacity of the fibre they yield for 
rope-making; secondly, that bird-lime is prepared from plants 
belonging to families which yield caoutchouc, as from the Apocyne- 
ous Voacanga in Madagascar; and in India, from different species 
of Ficus and Artocarpus. But the most interesting fact which I 
obtained from the investigation was one most unexpected and the 
least connected with the subject. Having been previously employed 
in considering the proper means for extending the cultivation of 
silk in India, it struck me as singular that so many of the plants 
which silk-worms prefer next to the mulberry leaf should be found 
in those families which yield caoutchouc. Thus, in England, the 
lettuce and dandelion leaves belonging to Cichoracem, and, in India, 
Ficus religiosa, belonging to Artocarpeae, have been ascertained to 
be the best substitutes for the mulberry leaves; while the Arrindi 
silk-worm of India, Phalmna Cynthia, feeds upon those of the 
castor-oil plants, Hicinus communis, belonging to Euphorbiace^e. 
Considering that a circumstance of this nature was not likely to be 
accidental, I was induced to think that it depended upon the pre¬ 
sence of some principle common to all these vegetables, and there¬ 
fore that caoutchouc (perhaps in a modified state) might really be 
contained in the juice of the mulberry, though this is described as 
not being milky. I, therefore, requested Mr. Sevier, who has 
made so many discoveries in the properties of caoutchouc, to 
ascertain whether my conjecture was well founded. In a few days 
he informed me that the mulberry-tree sap was of a milky nature, 
and did actually contain caoutchouc, especially on dry and bright 
sunny days.” 
