AND MORPHOLOGY OF APHIS. 205 
substance seems to occupy the whole central part of the chamber ; but on carrying the 
eye backwards, this clear mass is seen to be continuous with the two cords which I have 
above described as entering the second chamber (PL XL. fig. 3). 
The histological constitution of these bodies is at once sufficient to convince the observer 
that they are not ova, and I regard them as glandular masses which secrete the matter 
of the clear cord-like bodies which descend into the second and third chamber. 
The ova themselves, or rather the rudiments of the future ova, are not always to be 
seen with ease; and if the epithelium of the lower part of the apical chamber has become 
much altered, they cannot be detected: for they are visible exclusively in this part of 
the chamber, of whose epithelial cells they are, as I believe, merely a modification. 
However this may be, germinal vesicles and spots of all sizes intermediate between that 
of the ovum of the second chamber and that of an ordinary epithelial cell are seen in 
close contact with the parietes of the chamber. I have detected as many as six in this 
position. When the chamber is subjected to compression they may be set free, and are 
then seen to be surrounded by a zone of clear substance, the rudimentary vitellus. 
Under similar circumstances, the “glandular bodies” may also be isolated; when they 
present themselves as vesicles surrounded by a clear homogeneous substance, which is 
frequently prolonged at their apical extremity. It is gradually dissipated, and the inner 
sac set free by the action of water. 
I have not seen any ovarian ligament in the oviparous Aphis. 
The structure which I have described was wholly unexpected and new to me; and I am 
not aware that anything similar has yet been noticed in the ovaria of Insects*. I am 
inclined to believe that the glandular bodies contribute directly to the formation of the 
vitellus, because I have more than once seen cases, like that figured in Pl. XL. fig. 3, 
where the clear cord-like body appeared to pass directly into the mass of the ovum. 
There was always a widely open communication between the first and second, and 
between the second and third chamber; but the passage between the third and fourth 
was closed by the meeting of the epithelial lining. Does each ovum, as it is given off 
from the ovary, and passes backwards, carry with it a gelatinous mass, the product of one 
half of the glandular bodies, and only cease to be connected with these glands when it 
has taken the third place? 
Three cæca open into the dorsal side of the lower part of the vagina; of these the 
anterior single one is the spermatheca, the posterior pair are the colleterial glands 
(PL XL. fig. 1, m, n). r : : 
The spermatheca (x) is a sac with a narrow neck, dilated at its extremity, which opens 
considerably in advance of the colleterial glands, while its enlarged end lies between 
them. The duct of the spermatheca has thick walls continuous with those of the vagina; 
but its dilated portion is thin, and has a yellowish colour. It contains a multitude of 
large filiform spermatozoa bent upon themselves, and is very tough and resisting. 
The colleterial glands (m) are subeylindrical, but are constricted inferiorly where they 
* Unless, as I am strongly inclined to suspect from Leydig’s description, and from a bar gm — ‘pad E 
part of the ovaria of Coccus, the corresponding chamber of that insect’s remarkable ovaria presents a similar ure, 
See, however, the note which concludes this paper.) 252 
