164 PROF. W. H. JACKSON ON THE 



stage the oviclncal aperture is placed well in front of the anterior tubular end of the 

 sebaceous portion (cf. p. 185 on fig. 65), which is separated throughout its whole extent 

 on the ventral aspect from the hypodermis, the space between the two being occupied 

 by intrusive fatty tissue. The two tubular portions, the future glands, lie parallel to 

 one another, are sharply arched and curved upon themselves, and the portion common 

 to them at their point of origin is flattened dorso-ventrally, of fair lateral extent, but of 

 no great length (PL XIX. figs. 65, 66). As development proceeds the tubes show a 

 o-eneral increase in size, become a little tortuous, but continue to be curved upon 

 themselves. The common basal portion is a little shorter, slightly dilated on each side ; 

 the oviducal aperture is more directly beneath it, and consequently the tubular anterior 

 portion of the gland apparatus is nearly vertical and somewhat confused with the azygos 

 oviduct, as is seen from the sections PI. XIX. figs. 67, 68. All the changes just 

 detailed are more and more accentuated by degrees. The gland-tubes diverge from one 

 another laterally and are directed backwards, but as they lengthen, curve forwards at 

 their apices. The common basal portion is distinctly separated into a right and left 

 dilatation, connected as sections show (cf. figs. 67, 68) to the azygos oviduct by a 

 short and distinct tubular duct hidden in the vertical view beneath the common basal 

 portion. The oviducal aperture is now placed immediately below or slightly behind the 

 common basal portion of the gland tubes. Finally, as may be seen from PL XVII. 

 fig. 44, the duct (cl.v.gl.) connecting the two dilatations or vesicles of the sebaceous 

 glands to the azygos oviduct lengthens out, and the azygos oviduct itself extends 

 backwards (p.od' .), carrying its aperture, i. e. the oviducal or posterior aperture, with it. 

 As to the azygos oviduct. At first, that is to say at the time corresponding to fig. 38, 

 PL XVII., no change of any noticeable degree is obvious from what obtained at the 

 close of the preceding stage. Its anterior or bursal aperture lies just below the bases of 

 the bursal and receptacular outgrowths (PL XVIII. fig. 55 d), its posterior or oviducal 

 aperture is just at the anterior end of the sebaceous apparatus (PL XVIII. fig. 55/). 

 Both apertures are very minute and very close together. At the time corresponding to 

 fi°\ 40, PL XVIL, its anterior extremity is still solid, but the portion in front of the 

 bursal aperture is rounder in cross section than it was, and separated by a greater 

 distance from the hypodermis, fatty tissue intervening. The portion of the azygos 

 oviduct behind the bursal aperture and in front of the oviducal aperture is now clearly 

 separated from the hypodermis by a space filled with intrusive fatty tissue (PL XVIL 

 fi°\ 41). The oviducal aperture itself is nearly directly below the base of the sebaceous 

 vesicles. At the close of this stage the bursal aperture is connected by a tubular duct 

 (PI. XVIL fig. 45) to the azygos oviduct, and the oviducal aperture is still further 

 back, situated well behind the base of the sebaceous vesicles (PL XVIL fig. 44, 

 p.od'.). 



The paired oviducts "increase in size, and at the period to which fig. 40, PL XVIL 

 belongs have acquired a distinct lumen (PL XIX. fig. 60). The lumen is a fine 

 channel which appears to extend ventrally, or in other words it develops in a direction 

 proceeding from the ovary towards the azygos oviduct. It never communicates with 

 the latter until the parts have assumed the size and proportion shown in figs. 61, 62, 



