The Germ cells of Lophius. 583 



that there is a consistent increase in the number of germ-cells 

 during stages 6, 7 and 8, the average number in embryos of each 

 of these ages being respectively 3, 15 and 37. As previously 

 remarked, this increase in number might reasonably be interpreted 

 as an indication of the early multiplication period, but reasons 

 will now be given for thinking that this is not the case but that 

 this is in reality the early part of the period of rest. 



We may first note that during this period none of these cells 

 were actually observed in division and this indicates that this is 

 not a period of multiplication. This observation, however, is not 

 conclusive because it is entirely possible that such cells could not 

 be recognized during mitosis because of the disappearance of 

 their distinctive features. 



The relative size of the germ-cells and body cells furnishes more 

 satisfactory evidence on this point and indicates quite clearly that 

 the period of rest begins at about stage 6. It has already been 

 seen that in later stages the germ-cells are decidedly and increas- 

 ingly larger than the cells surrounding them and that this differ- 

 ence of size is due to the arrest of cleavage of the former. The 

 beginning of the difference of size marks the beginning of the 

 period of rest. In stage 6 the few germ-cells recognized do not 

 differ visibly in size from other cells of the primary entoblast 

 among which they lie (figs. 21, 22 and 23). In stage 7, however, 

 their nuclei are slightly but noticeablj' larger than those of sur- 

 rounding cells (fig. 28), while in stage 8 the difference is more pro- 

 nounced (fig. 29) . The arrest of cleavage has already resulted in 

 a difference in size which indicates clearly that the apparent in- 

 crease in the number of the germ-cells in these stages is not due to 

 an actual multiplication. 



During the study of these stages the explanation of the appar- 

 ent numerical increase came in an entirely unexpected manner. 

 Phenomena were observed which led to the conclusion that the 

 small size of the plasmosomes of the germ-cells is not primitive, 

 but that during the early part of the rest period there is an actual 

 reduction of their size by extrusion of substance from the nucleus. 

 It is also in connection with this process that the nucleus attains 

 its irregular shape, and not until this has taken place can the germ- 



