PLATE V 



EXPLANATION OF FIGURES 



Hydractinia echinata* X 2625 



1 Two egg cells resulting from the last oogonial division; n, diplotene stage 

 of spireme-thread; h, early bouquet-stage. 



2 Early bouquet-stage, showing loops centered in the nucleolus. 



3 Late bouquet-stage, showing the nucleolus pressed against one end of the 

 nucleus. 



4 to 8 Five stages in the early growth-period, showing the accumulation of 

 pseudochromatin-granules' throughout the protoplasm, the appearance of glob- 

 ules against the nuclear wall and oil in the protoplasm; semidiagrammatic. 

 Granules are represented by gray, oil by circles containing dots, nuclear globules 

 by circles containing parallel lines. 



5 to 11 Three later stages of the growth-period, showing the direct develop- 

 ment of the yolk-spheres from the pseudochromatin granules; semidiagrammatic. 

 Young yolk-spheres shown in gray. 



12 Egg about one-third grown, showing the appearance of mitochondria 

 between the simple yolk-spheres, some of which are now^ mature and possess a 

 different staining reaction ; semidiagrammatic. Mature simple yolk is represented 

 by circles; mitochondria by black rods, young yolk and oil as above. 



13 A nearly mature egg showing compound yolk-spheres in addition to the 

 above elements, as well as more mature simple spheres ; diagrammatic. Compound 

 spheres are represented by circles containing small circles. 



' All figures except those of plate 8 and figure 61 were drawn with a camera. 

 * All drawings were made from material fixed in Meves' or Flemming's killing 

 fluid unless otherwise stated. • , 



236 



