122 



BBITISH APHIDES. 



become mere pabulum for the support and development 

 of this one egg of great size. 



Prof. E. Gr. Balbiani states, however, that there is a 

 constant identity of number in the ovigerous tubes of 

 the oviparous Aphis, and in the tubes which give rise 

 to the living young of the viviparous Aphis of the 

 same species. More than this, he says that there is a 

 numerical relation between the number of ovaries and 

 the number of the spermatic capsules in the male. He 

 thinks, however, that of these last, some may coalesce, 

 and others may sometimes become arrested in growth. 



Whilst the sperm-capsules of the male Aphis are 

 always free and unattached at their summits, the 

 ovarian tubes of the female are always, according to 

 Balbiani's experience, united amongst themselves by 

 terminal filaments of great tenuity. Much is yet 

 uncertain as to the final attachment of the anterior 

 portion of these filaments to a dorsal vessel.* 



As examples occurring in the genera Siphono- 

 phora, Aphis, Drepanosiphum, &c, may be cited the 

 following : 



Ovar 



Siphonophora sonchi 



Aphis persicce 



Ap>his genista (rumicis ?) 



Siphonophora sol'uhujiu is 



Threpa/nosi/phv/m platanoides 



Lachnus agilis 



( 'hut'tophorus populi 



4 a.— THE MALE APHIS AND ITS REPRODUCTIVE 

 ORGANS. 



The occurrence of this sex amongst Aphides is 

 comparatively rare. Some explanation of this paucity 



* Balbiani, ' Mem. sur la Generation des Apbides,' p. 5, 1870. I 

 have often seen tbese ligaments in the pseudovaria, but, like Prof. 

 Huxley, I have not met with them in the true ovaria. — G. B. B. 



