Btgelow. — Nuclear Cycle of G-onionemus murbachii. 



PLATE 6. 



Figures 124-130 from isolated cells; figures 131-139 from sections. 



Figs. 124-126. Late pseudoprophase. The nucleolar shell has broken down, 

 leaving a persistent plasmosome. The chromatin is entirely 

 condensed into " beaded " segments. X 2600. 



Fig. 127. Regression of pseudoprophase. The chromatin segments are irregular 

 and have commenced to break down. X 2600. 



Fig. 128. Later stage in regression. The chromatin segments have largely broken 

 down. The plasmosome has grown much larger. X 2G00. 



Fig. 129. " Resting " stage of oocyte, following the pseudoprophase. The nucle- 

 olus is a homogeneous structure. X 2600. 



Figs. 130-138. Growth stage of the oocyte. 



Fig. 130. The chief nucleolus has become vacuolate, and an accessory nucleolus 

 has been formed. The chromatin is finely diffused and has largely 

 lost its staining capacity. X 900. 



Fig. 131. Later stage. The chromatin, which has regained its affinity for stains, 

 consists of a large number of angular masses of granules. Both chief 

 and accessory nucleoli, as well as the nucleus as a whole, have in- 

 creased greatly in size. X 900. 



Fig. 132. Still later stage. The chromatin masses have become arranged in 

 strands, many of which are in the form of Y's and Vs. X 900. 



Fig. 133. Section of late stage in the growth period, showing segments of numer- 

 ous chromatin strands. The chief nucleolus contains five vacuoles. 

 X 900. 



Figs. 134, 135. Chief nucleolus of oocyte. The ground substance contains deeply 

 stained strands. X 2600. 



Fig. 136. Chief nucleolus, containing many deeply stained strands and granules. 

 X 2600. 



Fig. 137. Chief nucleolus, ordinary type, containing vacuoles. X 2600. 



Fig. 138. Chief nucleolus. The walls of the vacuoles are deeply stained. 

 X 2600. 



