8 



GENERAL EMBRYOLOGY 



or the daughter cells, not scattering as separate individuals, 

 may remain associated during division and growth, forming a 

 colony of organically related cells which as a whole is to be 

 regarded as the individual organism. Among nearly all of 

 these colonial or compound forms the entire colony, or cwno- 



FIG. 7. The formation and development of the statoblast, in the fresh water 

 Bryozoan, Cristatella. A. After Braem. Others, after Verworn. A. Longi- 

 tudinal section through the funiculus, showing the relations of the statoblast. 

 B-E. Optical sections of stages in the development of the statoblast. F. Sec- 

 tion showing rudiment of embryo, e, superficial ectoderm; i, inner layer of 

 funiculus (ectoderm) ; o, outer layer of funiculus (endoderm) ; s, rudiment of 

 statoblast. 



bium as it is called, is not later involved as a unit in reproduc- 

 tion, but the component cells may individually undergo 

 fission leading to the formation of new colonies. In forms like 

 Pandorina or Platydorina all the cells are alike, and each repro- 

 duces, so that there may be as many new colonies formed as 

 there are cells in the original colony (Fig. 8). In other forms 

 the power of reproduction is limited to certain cells, termed 



