AND MORPHOLOGY OF APHIS. 207 



dissipated, and the central cord becomes less distinct ; l)ut 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 natui'c 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 Mnsca, Dexia, and Melophagus (Leuckart, ;. c. pi. 7. figs. 1, 2, 4, 5), reminds one 

 strongly of the envelope of the appendage in Aphis. 



The micropyles of lAbellula, Dexia, and Musca, again, exhibit a sort of " mouthpiece " 

 formed by a prolongation of the chorion surrounding the micropylar apertui'e. 



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 -svingless oviparous female of A. Persicce thus : — 



" The ovigerous cseca 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 ia general they acquired their hard covering 

 only in the tliii-d or last chamber, which in aU the females was occupied by a very lai-ge 

 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." {I. c. p. 89.) 



I 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 appears to me to be well 

 founded, for Uutrochet examined a viviparous female ; but I strongly suspect that he has 

 himself overlooked the " sebific " apparatus in the oviparous forms. 



Von Siebold states that the ovarian cseca of the oviparoiis Aphis LonicercB are divided 

 into only two chambers : — 



" In the undeveloped state the whole tube forms only a simple pyi-iform appendage ol 



• After describing the cup-iike micropyle at the anterior pole of the ovum of the Louse, Leuckart (/. c.) goes on 

 to say — " Besides this micropylar apparatus at the anterior pole, there is at the posterior pole of the OTum a structure 

 which attracts attention. It may be described as a blunt cone, which is attached rather on one side of the centre of 

 the posterior pole, and has acquired a peculiar striated appearance by reason of its longitudinal folds, and band-like 

 thickenings. The interior diameter of this structure measures ^'" ; the upper is less, about -^"' ; and the length is 

 about the same. A hollow space is contained within this body, so that it might be compared to a bell ; but it seems 

 as if from the roof, or cupola, as it miglit be termed, of this bell, a number of closely appressed elevations and points 

 depended. With respect to the import of this remarkable ajiparatus, I will only throw out the supposition that it is 

 an apparatus of attachment. For a long time I thought I had discovered in it a second micropylar apparatus ; but I 

 renounced this view when I was unable to discover any aperture in it." (p. 140.) 



