ABBREVIATIONS 



a, possible egg cells ov., egg cells 



ec, ectoderm pr., perisarc of the hydroid stem 



gl., gland cells sp., male germ cells 



PLATE 1 



EXPLANATION OF FIGURES 



1 Portion of female colony showing method of branching, position of hy- 

 dranths and of gonophores. The dots in the stems represent the position of egg 

 cells. A, B, C, are the portions of the stem shown in figs. 2, 3, 4, respectively. 

 X 11. 



2 Optical section of region A, fig. 1. The deeply staining cells in the ento- 

 derm include some egg cells and some gland cells. X 255. 



3 Optical section from region B, fig. 1. The deeply staining cells in the 

 entoderm are. egg cells. X 255. 



4 Optical section of stem from region C, fig. 1. Most of the shaded cells 

 are egg cells. The presence of large and small eggs in the same region suggests 

 their origin in this place; the shape of some eggs suggests a possible migration. 

 X 255. 



5 Optical section through a stem near the distal end of a colony, a region 

 devoid of gonophores. It is difficult to say which of the deeply staining cells 

 are gland cells and which eggs. X 473. 



6 Optical section of stem and polyp, the latter becoming a gonophore. Egg 

 cells present. X 150. 



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