GERM CELLS OF COELENTERATES 5 



formation of the reproductive bodies. This part of the theory is 

 estabhshed by making certain ontogenetic and phylogenetic im- 

 plications concerning the degeneracy of the gonophores and the 

 origin of germ cells in the stem and not in the gonophore. These 

 implications are not firmly grounded upon fact. 



This later theoretical position of Weismann is the one which 

 has been generally accepted and is the position almost univer- 

 sally taken in text- and reference books and in general papers not 

 dealing specifically with the subject of germ cells of coelenterates. 



2. OBSERVATIONS UPON EGG CELLS 



Study of entire stems. Examination of a stained and cleared 

 portion of a female colony, such as is shown in figure 1, usually 

 shows a number of deeply staining cells, some large and others 

 small, scattered through the stem. The large cells appear as 

 growing eggs and the small ones seem to be like them except in 

 size. The impression gained from the study of such a prepara- 

 tion is that of a considerable number of egg cells scattered 

 through the colony and widely distributed along the stems of 

 the hydroid. 



A detailed and careful study of these cells was made and their 

 distribution plotted. About sixty slides, made by staining and 

 mounting entire portions of different colonies made up of stems, 

 branches, polyps, and gonophores, were examined. These ob- 

 servations demonstrated that the deeply staining cells were not 

 universally distributed, but were more or less localized in certain 

 regions, especiallj^ in the branches which come from the main 

 stem of the hydroids. Figure 1 is a camera outline of a part 

 of a colony in which the dots mark the position and relative 

 size of the deeply staining cells. In all such preparations the 

 hydrorhiza and main central stem of the hydroid showed no 

 deeply staining cells, the bases of the branches arising from the 

 main stem were likewise devoid of such cells, but further distal- 

 wards they were present, sometimes in considerable numbers. 

 The pedicels of young lateral hydranths and of gonophores, as 

 well as the distal and younger parts of the lateral branches even 

 where hydranths and gonophores were absent, were the regions 



