AND MORPHOLOGY OF APHIS. 207 
dissipated, and the central cord becomes less distinct ; but I have never yet seen it dissolved, 
and sometimes it seems altogether to resist the reagent. The rounded tubercle of the 
chorion to which it is attached, however, now clearly exhibits a central funnel-shaped 
body, continuous with the axis of the appendage, and appearing like a canal (fig. 4, C). 
Is this a micropyle, and what is the nature of the appendage? I regret that I have 
not the leisure to pursue the inquiry far enough to answer this question satisfactorily ; but 
I incline to think that the micropyle is really situated here*. 
The albuminous papilla surrounding the bundle of spermatozoa in the impregnated 
ova of Musca, Dexia, and Melophagus (Leuckart, l. c. pl. 7. figs. 1, 2, 4, 5), reminds one 
strongly of the envelope of the appendage in Aphis. 
The micropyles of Libellula, Dexia, and Musca, again, exhibit a sort of “mouthpiece ” 
formed by a prolongation of the chorion surrounding the micropylar aperture. 
The account which I have given of the reproductive organs of the oviparous Aphis is 
in general agreement with that of other observers. Morren describes the reproductive 
organ of the wingless oviparous female of 4. Persicæ thus :— 
“The ovigerous cæca well deserved their name; for no foetuses were any longer visible 
in them. Each was exactly composed of three chambers, of which the first or terminal 
was enlarged and spherical, and filled with twelve to twenty-four little, well-formed ova, 
yellow in the centre, and white peripherally. These ova descended into the second cham- 
ber, and then elongated and enlarged; but in general they acquired their hard covering 
only in the third or last chamber, which in all the females was occupied by a very large 
ovoid greenish ovum. These ova became covered at the same time with the sebific liquid ; 
for some were seen to be provided with a little appendage intended to fix them to the 
bodies in which the parent lays them. This appendage was mucous, and arose from a 
thickened viscous liquid.” (2.:c. p. 89.) ! n 
1 recognize in Morren's “twelve to twenty-four ova” the ovarian glands which I have 
described. His microscope was obviously inadequate to show him the true ova; but it 
seems difficult to suppose that in this species there is, as he maintains, neither colleterial 
glands nor spermatheca. His objection to Dutrochet’s statements appeårs to me to be well 
founded, for Dutrochet examined a viviparous female; but I strongly suspect that he has 
himself overlooked the “ sebific” apparatus in the oviparous forms. a 
Von Siebold states that the ovarian cæca of the oviparous Aphis Lonicere are divided 
into only two chambers :— ` : å 
“In the undeveloped state the whole tube forms only a simple pyriform appendage of 
* After deseribing the cup-like micropyle at the anterior pole of the ovum of the Louse, Leuckart (/. c.) goes on 
sn there is at the posterior pole of the ovum a structure 
“ Besides this micropylar apparatus at the anterior pole, 
å S s attached rather on one side of the centre of 
Which attracts attention. It may be described as a blunt cone, which i x 
the posterior pole, and has ahis a peculiar striated appearance by reason of its longitudinal folds, and band-like 
thickenings. The interior diameter of this structure measures gl" ; the upper is less, about vr 5 and ee z 
about the same. A hollow space is contained within this body, so that it might be compared tos pn; bu i er 
3s if from the roof, or cupola, as it might be termed, of this bell, a number of closely appressed elevations = DE n 
depended. With respect to the import of this remarkable apparatus, I will only throw v the remis TIAM 
an apparatus of attachment. Fora long time I thought I had discovered in it a second micropylar apparatus ; 
“nounced this view when I was unable to discover any aperture in it.” (p. 140.) 
