IS TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



their nuclei are about 10 microns in diameter. As growth 

 proceeds a change takes place: the cell nearest the tube, 

 known as the body-cell, grows more rapidly than the 

 stalk-cell, so that a week later, when they migrate into 

 the tube, the stalk-cell nucleus is IT microns diameter, 

 and the body-cell nucleus 24 microns diameter. The tube 

 nucleus is oval in shape, its two diameters in March 

 being 18 microns and 13 microns ; a month later, when 

 the body and the stalk cells migrate, its two diameters 

 are 24 microns and 15 microns ; at this period it is densely 

 surrounded by starch grains. 



By the second week of April the cells surrounding the 

 gametophyte have become so lax that they can scarce be 

 described as forming a tissue ; the gametophyte still 

 remains a hollow globe containing parietal nuclei only. 

 The ovule has grown to a length of 1*3 mm. ; the nucellus 

 is about 30 cells deep from its apex to its junction with 

 the tabular cells which form a wall enclosing the lax 

 tissue surrounding the gametophyte, nearly half of this 

 depth is occupied by the pollen tubes and their branches. 



At this period there is evidence of great mortality 

 amongst the young gametophytes ; in fact this may be 

 said of the whole period commencing with the organisa- 

 tion of the megaspore in July till about the middle of the 

 May following, when the archegonia are initiated. 

 During this interval many ovules may be found in which 

 the gametophyte is in course of disintegration, others in 

 which no trace of one can be discovered. The ultimate 

 fate of such ovules can only be conjectured ; doubtless in 

 some, growth is at once arrested, such would possibly 

 account for the small brown kt specks " that are found 

 during the third season occupying the place of ovules ; 

 others may continue growth and become the empty husks 

 that are found in ripe cones. 



