94 MARGARET C. FERGUSON 



Where adjacent archegonia crowd against each other these cells 

 early become distorted and partially destroyed. It is often diffi- 

 cult to demonstrate the presence of cross walls in the arche- 

 gonium-sheath. Neither have I been able to satisfactorily 

 demonstrate the presence of pores in the wall separating the 

 sheath-cells from the egg. Hofmeister ('6i-'62), Goroschankin 

 ('80, '81), Arnoldi (bo), and Coulter and Chamberlain ('01) all 

 describe this wall in Pinus as thick and furnished with pores ; 

 but if such is the case it is not apparent in my material. On the 

 contrary the wall seems very thin and is scarcely differentiated 

 from the ectoplasm. It may be that further search on my part 

 will reveal both the " pits " and the " thickened wall," but thus 

 far I have not detected either. 



No special attempt has been made to count the number of 

 chromosomes in the nuclei of the various parts of the sporo- 

 phyte and gametophyte, but whenever a nucleus was observed 

 in which the chromosomes were particularly clear and distinct 

 their number was always noted. In such cases twelve chromo- 

 somes have invariably been counted in the nuclei of the sheath- 

 cells. Chamberlain ('99) has found the same number in the 

 corresponding cells of Pinus Laricio. The early development 

 of the archegonium, as just described, agrees in the main with 

 that given by Strasburger in 1878. 



As the archegonia grow the prothallium also continues to 

 increase in size, several layers of cells being formed above the 

 archegonia, except over their neck-cells. Here no prothallial 

 tissue is laid down, so that there arises an opening in the endo- 

 sperm leading from the neck-cells of each archegonium to the 

 nucellar cap (figs. 177-180). The presence of funnel-shaped 

 openings leading from the nucellus to the archegonia-necks in 

 Pinus was noted by Hofmeister in 1851 and their origin was 

 correctly described by him in 1862. In the last stages of pro- 

 thallial development preceding fertilization, the sides of this 

 tubular cavity often become very closely crowded together so 

 that the passage is obscured. 



The number of archegonia in a single ovule varies in Pinus 

 Strobus, P. rigida and P. resinosa from one to five, the usual 

 number being three. In Pinus austriaca and P. montana var. 



