PROCESS OF EGG-MAKING IX A TKEMATODE. 2$ 



sections makes it quite clear that the germ duct {c) and the yolk 

 duct (d) connect in such manner that when amass of yolk rushes 

 along the yolk duct past the opening of the germ duct and into 

 the common duct (Fig. 3, d, c,y, and arrow) sufficient suction is 

 created to draw a germ from the germ duct. 



Since the amount of yolk which is necessary for a single &gg is 

 automatically emptied into the yolk duct, the whole reflex has 

 become adjusted with such marvellous nicety, the several parts 

 to each other, that it seems probable that just enough suction is 

 created to draw a single waiting germ cell from the germ duct 

 which thus Joins the passing charge of yolk. 



The stimulus which causes a discharge from the seminal duct 

 {sd, sd') into the common duct always to take place immediately 

 upon the completion of the process of molding the egg-shell is, 

 of course, not obvious. The whole complicated process is an 

 intricate nerve reflex. 



Egg-making was observed to proceed actively for ten minutes 

 or more to be followed by a short interval of rest. The time 

 occupied in making an egg was not noted until the specimen had 

 been under observation for two or three hours, by which time 

 the worm had doubtless lost some of its vitality. When noted, 

 the time from the moment at which the yolk left the reservoir 

 until the completed egg was ejected into the water was about 40 

 seconds. , 



Summary of Events. 



1. A mass of yolk leaves the yolk reservoir (jr), 



2. As the yolk mass passes the germ duct(<:) a germ is drawn 

 out by the suction created by the moving mass of yolk, 



3. The yolk mass and germ together pass along the common 

 duct {cd) to the ootype {em). 



4. An egg is molded into a tetrahedral shape by a kind of 

 hammering action of the walls of the ootype, at the same time a 

 shell is formed, its substance being secreted by the shell-forming 

 gland. 



5. A slowing up of the action of the ootype is followed by the 

 appearance of a minute cluster of sperm in the common duct 

 {sd\ s). 



This cluster of sperms comes from the seminal duct and passes 

 along the common duct to the ootype. 



