25 



(Iocs not cut off a parietal cell ; a tetrad row of megaspore 

 mother-cells separated by walls is produced ; the lowest 

 one of the four functions as the embryo-sac. 



3. The Embryo-sac divisions are normal up to the 

 8 -celled stage ; number of chromosomes in the reduction 

 division, 8 ; there is a large development of antipodal 

 tissue. 



4. Evidence in favour of self-pollination and self- 

 fertilisation ; the pollen-tube grows down an intercellular 

 canal of a stigma branch ; passes through stylar-conducting 

 tissue ; enters the ovary cavity and takes a course between 

 the lining layer and the outer integument ; strikes through 

 the micropyle already forced open by the egg-apparatus. 



5. Pollen-tube passes into a synergid and discharges 

 contents ; the foremost generative nucleus probably unites 

 with the two extra-polar nuclei to form the endosperm 

 nucleus - " vegetative fertihsation." The second sperm 

 nucleus combines with the egg nucleus — " sexual 

 fertilisation." 



6. Divisions of the fertilised egg seem to follow 

 Cannon's description given for A:ciia faiun ; the embryo 

 is derived from the apical cell onl)- ; the suspensor is the 

 original primary basal cell. 



7. The antipodal tissue and endosperm act as 

 conveyors of food material to the embryo ; their physio- 

 logical connection with the question of alternation of 

 generations ; the chemical nature of the carbonaceous and 

 nitrogenous reserves. 



CONCLUSION. 



If apology be needed for emphasising physiological 

 considerations of nutrition and reproduction in their 

 relations to the question of alternation of generations, it 

 is the vast importance attaching to those phenomena in 



