704 THE GENERATIVE ORGANS. 
cords) unite and give origin to the whole system of sexual 
ducts is incorrect: they only form the vasa deferentia (my 
vasa efferentia) or the oviducts. 
(2) All the other parts of the efferent canal are developed 
from the hypodermis. 
(3) The connective tissue and muscaluture are derived from 
the mesoblast. 
(4) The efferent ducts originate as paired rudiments; all the 
azygos parts of the efferent apparatus are at first paired. The 
azygos efferent apparatus of Insects must, therefore, be re- 
garded as morphologically a secondary and more complicated 
form. 
(5) The male and female efferent ducts are strictly homolo- 
gous. 
(6) The cavities of the oviducts arise independently, and 
come into relation secondarily with the primitive ducts of the 
gonads, which are developed from the solid genital cord. 
Hatchett Jackson [851], in an important memoir on the 
development of the oviducts and accessory sexual apparatus in 
Vanessa Io, has shown conclusively, I think, that the bursa, 
vagina and azygos oviduct of this insect are developed from 
the hypodermis, which are at first paired pouches, imaginal 
discs. These pouches unite and form an open groove on the 
ventral surface of the pupa from which the bursa and azygos 
oviduct are subsequently developed. The author has not 
apparently investigated the manner in which the paired ovi- 
ducts arise, but assumes that they are formed from the genital 
cords. 
The Genital Cord in the Blow-fly undoubtedly becomes con- 
verted into a hollow epithelial tube surrounded by a peritoneal 
investment of extreme tenuity at a very early period in the 
development of the pupa. On the sixth or seventh day of the 
pupa stage, I have succeeded in dissecting out the whole of 
the genital ducts and ovaries. A drawing of the preparations 
is given in Fig. ror. It will be seen that the genital cords 
have indubitably become the tubular parovaria. The anterior 
ends of these organs are closed, and are imbedded in the 
