PLASMA-STRUCTURE IN EGG OF HYDRACTINIA 199 



D. EARLY GROWTH PERIOD 



1 . Nuclear reconstruction 



The growth-period begins directly after the preceding stage, 

 both nucleus and protoplasm increasing in size. Nuclear changes 

 appear, which result in the reconstruction of 'the nucleus; that is, 

 the densely staining smooth chromatin-loops break up into a 

 coarse, open, granular net, the threads of which center in the 

 nucleolus and radiate to the periphery of the nucleus (figs. 4, 5, 6). 

 The granules of chromatin are conspicuous in this period at the 

 nodes of the net, while a few fine granules he against the inner 

 wall of the membrane. By the time this stage is reached the 

 chromatin takes most basic stains somewhat less intensely than 

 previously, and may even fail to stain with most basic dyes or 

 take the plasma stain instead. The latter condition is striking 

 when eggs fixed in either sublimate-acetic or picro-acetic killing 

 fluids are stained with thionin and eosine or Auerbach's fluid. As 

 the egg grows, the radial arrangement of the nuclear net is lost 

 (figs. 7, 8, 18) until by the time the egg has reached the gonophore 

 the chromatin is coarsely granular, with little evidence of the net- 

 like arrangement left. At the same time, its affinity for basic 

 dyes has continued to diminish (figs. 19, 20, 22, 25, 26, 27, 28). 

 A more complete accoimt of the disappearance of the net is given 

 later. 



2. Pseudochromatin-granules 



When but a slight increase in the size of the egg has occurred 

 and when the above nuclear changes are occurring, there appears 

 throughout the protoplasm a fine granular precipitate ('Emission 

 stage' of Schaxel) which, as a rule, takes the basic stains (figs. 4, 5, 

 6). The granules of which this substance consists I will call 

 'pseudochromatin-granules.' Striking differences appear in the 

 form and staining reactions of these granules as a result of 

 different modes of fixation. After Meves' method of fixation, 

 they are fine and evenly distributed throughout the egg. If 

 stained with iron-hematoxylin they appear gray in color while 

 the chromatin is deep gray or black. If stained according to 



