192 Bionomics of Cryplialus abietis 



usually enter the lower portion of the uterus (the vagina) prior to the 

 entrance of the bursa copulatrix.) 



According to Nusslin^ the bursa copulatrix in the genus Cryphalus 

 is obscure or abs6nt. From repeated dissections of the female repro- 

 ductive organs in all stages of development for the purpose of investi- 

 gating this point I should say rather that the receptaculum seminis 

 is the obscure portion of the reproductive apparatus, for it is only in 

 the reproductive organs of females that have just completed egg-laying 

 that the position and outline of this part is traceable at all. In all stages 

 of the development of the reproductive organs of the female I have 

 found the bursa copulatrix quite easily discernible but at the same time 

 there is no distinct line of demarcation between it and the receptaculum 

 seminis. In my opinion the bursa copulatrix encloses the receptaculum 

 seminis in its anterior end and this can be a possible reason for its 

 obscurity. 



The sequence of changes which I observed to take place in the 

 reproductive organs of the female during their transition from the 

 immature to the mature state and to their condition after egg-laying 

 may be summarised as follows : 



In the immature state (Fig. 12) the egg-tubes are colourless and are 

 comparatively uniform throughout their length. The bursa copulatrix 

 is colourless and empty while the receptaculum seminis enclosed within 

 it is scarcely traceable. The accessory gland of the receptaculum is 

 small and inconspicuous. 



The first noticeable change in the reproductive organs is the slight 

 narrowing of the lower portion of the egg-tubes while the contents of 

 this portion become muddy coloured. Later some of this muddy coloured 

 substance passes down into the oviduct which now becomes much 

 swollen. Following on this, the egg-tubes, by a shunting-off process 

 which takes place in the middle or posterior portion of each tube, 

 become more elongated. Soon the egg-tubes divide up in bead-like 

 fashion, each bead or egg-chamber containing an egg. In this stage, 

 depicted in Fig. 13, we see that the oviduct is still swollen; the bursa 

 copulatrix is full and is muddy in colour and the receptaculum seminis 

 enclosed in the bursa copulatrix is still obscure. As soon as an egg has 

 passed through the neck or lower portion of the egg-tube (see Fig. 14), 

 this portion contracts, swelling out and contracting again each time an 

 egg passes through it. From Fig. 14 it might seem that an egg is passed 

 into the oviduct first from one ovary then the otlier in turn. 



' See Hopkins, p. li)5. 



