56 PETER OKKELBERG 



Very little was known concerning the processes that take place 

 in the oocyte of any animal preliminary to its growth period, 

 until von Winiwarter ('01) published his extensive observations 

 of this period in the cat and in man. Based upon changes which 

 take place in the nucleus, he divided the transition period from 

 the oogonium to the oocyte into the following periods: 1) Noy- 

 aux protobroques; 2) noyaux deutobroques ; 3) noyaux leptotenes; 

 4) noyaux synaptenes; 5) noyaux pachytenes; 6) noyaux diplo- 

 tenes, and, 7) noyaux dictyes. In a later publication by von 

 Winiwarter and Sainmont ('09) another stage has been added 

 between the first two, namely, noyaux poussieroides. Other 

 investigators have divided the period differently and have 

 applied other terms to the different phases, but on the whole the 

 processes taking place in all animals in which the synapsis phase 

 has been studied seem to follow the general course outlined by 

 von Winiwarter, In the lamprey the changes correspond in the 

 main with those of other forms studied. An abbreviated list of 

 the above stages has already been given (table 1). 



Nuclear changes. Early leptotene. After the last oogonial 

 division the germ cell enters a period of rest, during which the 

 chromatin of the nucleus becomes broken up into small particles 

 (fig. 52). These are scattered throughout the whole substance 

 of the nucleus so as to make its contents appear almost homo- 

 geneous. There are no very distinct chromatin bodies in the 

 nucleus at this stage and the only stainable parts are a very fine 

 network and two very distinct plasmosomes. This stage cor- 

 responds to the stage in the germ cells of the cat described by 

 von Winiwarter and Sainmont ('09) as 'noyaux poussieroides,' 

 and to the stage in the germ-cell history in Proteus described by 

 Jorgensen ('10) as 'erste Zerstaubung.' 



Sonnenbrodt ('08) studying this period in the germ cells of the 

 chick, found that the chromatin at this stage was very small in 

 amount, and he believes that the period succeeding the last 

 oogonial division is devoted largely to the formation of new chro- 

 matin. He says it ''besteht in der Hauptsache in der chromatin 

 x^ufnahme oder richtiger Chromatinbildung." In the lamprey, 

 too, the chromatin network begins to reappear at a somewhat 



