154 Embryonic Development of Chironomns 



brownish eggs are embedded. The eggs do not lie at 

 random in the cylinder, but are lodged in a special 

 winding tube or egg-pipe, which lies near the surface 

 of the egg-mass, and makes many almost complete spires, 

 curving round from right to left and from left to right 

 alternately. The tube itself only becomes visible when 

 the egg-mass is boiled or treated with hardening agents. 

 The interior of the cylinder is traversed by interwoven 

 cords, which are more fully described on p. 155. As 

 many as nineteen spires have been counted on one egg- 

 mass, and since each spire commonly contains about 

 forty-five eggs, the total may amount to 850 or even 

 more ' . 



The various forms of egg- rope which characterize dif- 

 ferent species of Chiron omus reach a climax of complication 

 in C. dorsalis. In simpler cases the eggs may be enclosed 

 in a globular or pear-shaped gelatinous mass, which is 

 glued to a stone in the bed of a stream (fig. 116). Or the 

 eggs may lie, almost at random, within a gelatinous pipe. 

 Both a pipe, enclosing the eggs, and an outer gelatinous 

 envelope may be present, and the pipe may be thrown 

 into bends or spires which do not affect the outer cover- 

 ing. Lastly, a pair of interwoven cords may be added, 

 which traverse the cylinder, on whose outer wall lie the 

 spires of the egg-containing jDipe. The egg-mass may 

 contain three different kinds of gelatinous substance, one 

 forming the pipe, a second the general investment, a third 

 the interwoven cords. The two latter may be furnished 

 by the gluten-gland, whose cavity when cut across shows 

 sectors of what are probably two different secretions 

 (fig. 84) ; the wall of the egg-pipe is perhaps secreted 

 by the ovary or oviduct. 



Since the larvae which issue from the eggs have to 



' In seven egg-chains (ho numbei" of eggs was estimated at 668, 784. 

 817, 818, 828, 912, and II03. 



