PRIMARY AND SECONDARY SEXUAL CHARACTERS IN LEPIDOPTERA. 201 
between two correlated parts, he would substitute a ‘‘food-bond,”’ or, 
in other words, a chemical one, and he adds: ‘‘To revert to the 
illustration already borrowed from the stag, if the influence be purely 
nervous, as is commonly believed, the path by which it is conveyed all 
the way from the testes to the horns over the intricate and interlacing 
lines of the sympathetic system is hard to conceive, but substitute. a 
food-bond, and the connection is at once obvious and easy of com- 
prehension.” 
After showing that in plants structure largely depends upon food, 
and that the profound modification of the plant protoplasm in the 
formation of galls, is possibly due to the fact that the peculiar 
substance injected into the tissues of the plant plays the part of food, 
‘‘ not however in the ordinary sense of nourishing, but rather in that 
of combining and uniting with the protoplasm or one of its con- 
stituents, after the manner of a chemical agent, and so altering its 
molecular constitution and affinities as to change it into something 
altogether different from what it was before.” He then concludes: 
“of such a kind is the nature of the ‘food-bond,’ which I would 
suggest may underlie some of the phenomena of correlation, that is, 
certain substances are secreted by the controlling organ, which 
combine chemically with the protoplasm of the correlated part and 
endow it with new capabilities.” 
If we are unable to accept this view, it is not because we do not 
fully appreciate the exceedingly clever suggestion made by Dr. Wood 
to explain a difficult subject, but because we are unable to apply his 
reasoning to definite cases that have come under our notice. 
Take for example, first, the case of those bilaterally eynandro- 
morphous examples of lepidoptera—Tvrichiura crataegi, Lasiocampa 
quercts, Malacosoma castrensis, M. neustria, &c.—that are known to all 
entomologists, and several of which we have described at length in our 
recently-published second volume of Vhe Natural History of the British 
Lepidoptera. In these the external portions of the sexual organs are 
on one side male, on the other female, presumably the internal 
portions of the organs are so also, and as a result the side which 
possesses the seminal glands presents all the secondary sexual charac- 
ters of the male—antenne, lees, shape of wings, markings, colour 
(both of head, wings, and thorax)—whilst the side which possesses 
the ovaries presents all the secondary sexual characters that dis- 
tinguish the female. So complete is the division that a central line 
divides the insects into two distinct halves, male on one side female 
on the other. I-cannot understand a food-bond that is not diffused 
throughout the whole system. Are we to understand that the internal 
secretions from the ovaries of an individual such as I have described 
can be absorbed only by one side of the insect, and similarly that the 
internal secretions of the seminal glands can only be absorbed by the 
opposite side ? 
A second elass of gynandromorphous individuals differs widely from 
the first. These appear to have the ovaries developed in part on either 
side of the insect and similarly the seminal glands. Such individuals 
will present the general characters of a male or of a female, according 
as the male or female genital organs are best developed, with sundry 
areas and structures on either side of the insect showing characters of 
the opposite sex to that which is generally exhibited by the insect. 
