22 TRANSACTIONS LIVER POO I, BIOLOGICAL SOCIETY. 



degenerate, practically leaving the whole cavity of the 

 venter free to the cytoplasm of the egg cell. The nucleus 

 of this cell when first cut off is often very small — its size 

 varies considerably — but it is usually about 50 microns in 

 diameter ere it leaves the spindle. It at once passes to 

 the centre of the egg, by which time it has acquired a 

 diameter of about 100 microns; it is frequently 130 

 microns in diameter. By this time the cytoplasm of the 

 egg has undergone a great change, its vacuolate condition 

 has given place to one of compactness, it is for the most 

 part finely granular ; around the nucleus may frequently 

 be seen dense threads radiating into the granular mass ; 

 immediately within the egg wall there are a number of 

 globular bodies, somewhat nuclear like, known as 

 " proteid vacuoles." In the cytoplasm near the apex of 

 the cell there is a distinct oval shaped cavity. The egg is 

 now ready for fertilisation. 



Here it will be convenient to refer again to the male 

 gametophyte. We have already noted that the generative 

 cell divides during the second week of April — about 

 April 11th — giving rise to the body- and stalk-cells and 

 that they pass from the grain into the tube a week or ten 

 days later — April 21st. There appears to be, however, 

 great latitude as to the time of their migration, for 

 examples are found in which this has taken place so late 

 as June 6th. 



The body-cell divides to produce the sperms — gametes 

 — during the third week of June. Since their fresh start 

 in spring the tubes and their branches have grown but 

 little, in fact the amount is frequently almost imper- 

 ceptible ; with the advent of the sperms, however, the 

 growth of the tube proper is very rapid, for within a week 

 — probably in two or three days — it has pierced the 

 nucellus and entered the egg by way of the funnel-shaped 



