BIOLOGY OF PARACOPIDOSOMOPSIS. 369 



embryos do not appear until after dissociation has taken place. 

 The production of asexual larvse in a given polygerm is not 

 confined to a single period of development, but is a continuous 

 process, extending from the third to about the fifteenth day. 

 Sections of practically every polygerm from twelve to fourteen 

 days old will show asexual individuals in various stages of 

 development, from young embryos to fully developed larvae. 



The method of their development in the American species 

 is very similar to that for Litomastix as described by Silvestri. 

 The main difference is that they frequently appear in groups, 

 instead of arising singly from certain of the secondary masses. 

 This is also true for some of the early cases (Figs. 9, n). Fig. 14 

 is a section passing through a group of asexual embryos imbedded 

 in adipose tissue. In the upper right-hand corner of the figure 

 is a group of secondary masses about on the point of developing 

 into sexual embryos. They are easily distinguishable from the 

 asexual embryos by their comparatively small size. Several 

 other series show this same condition. Single embryos or small 

 groups of two or three do, however, appear in some of the series. 



After the period of multiplication of secondary masses is 

 closed, that is in stages fourteen or fifteen days old, the body 

 cavity of the host contains many groups of asexual embryos 

 (Figs. 15, 1 6, 12) as well as groups of young asexual larvae. In 

 each of two series a group of ten or twelve individuals was found. 

 There are also found free asexual larvae (Figs. 20, 21, 22), and 

 some that are on the point of being set free from the capsule 

 (Fig. 1 8). That single asexual larvae may develop in conjunction 

 with a group of sexual embryos is clearly evident in two instances. 

 In Fig. 17 a young asexual larvae is closely associated with a 

 group of sexual embryos, and in Fig. 19 a large asexual larvae, 

 just freed from its capsules, is still attached to a mass of embryos. 



The frequent appearance of asexual embryos or larvse in groups 

 suggests that, like the sexual embryos, the individuals of a group 

 have a common origin, probably arising through the division of 

 a single secondary mass. 



Since one cannot follow the course of development of a single 

 egg, but must depend upon series of sections, it is impossible to 

 determine whether every polygerm eventually produces asexual 



