38 J. T. PATTERSON 



While some polygerms produce asexual embryos at a very 

 early stage, nevertheless the majority of such embryos do not 

 appear until after dissociation has taken place. Their produc- 

 tion 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. They arise during both the 

 secondary- and tertiary-mass stages. 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. 



During the secondary mass stage one is struck by the frequence 

 with which they are found in groups. In some groups there 

 may be as high as ten or twelve individuals. Figure 74 shows 

 one of these groups embedded in fat. A group of tertiary mass 

 from this same polygerm is seen in figure 75. 



The frequent appearance of asexual embryos or larvae 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 or tertiary mass. 



Single asexual embryos also develop, in conjunction with a 

 group of sexual embryos. In one case I found an asexual em- 

 bryo joined to a single sexual embryo, which is still in the morula 

 stage. In figure 81 is a group of ten sexual embryos and one 

 asexual embryo all held together by their membranes. In fig- 

 ure 83 is a fully developed asexual larvae, freed from its capsule, 

 but still connected by the head to a group of sexual embryos. 



In developing into a larvae the asexual embryo becomes bent 

 upon its long axis, with the ventral surface forming the concave 

 side (fig. 72, As.E.). Just before escaping from the capsule, 

 the larva has a characteristic shape, like the letter C (fig. 82). 

 Once set free, the larvae present various figures, such as are 

 seen in figures 83 to 86. 



The asexual larvae invariably degenerate, apparently they do 

 not live over three days as free larvae. The first free larvae 

 appear on the twelfth day, and degenerating specimens are 

 found on the fifteenth day. The last larvae escape from their 

 capsules on the sixteenth day and none are found after the 



