THE SEED PRODUCTION OF PIN US SYLVESTRIS. 11 



By the end of September they are about '75 mm. in 

 diameter and 10 mm. in length; the protuberances have 

 increased in number and extend about half-way up the 

 cone, at the end of October they cover the whole cone, 

 thus faintly indicating the scales and bracts that are to 

 be. They are now about 1*0 mm. in diameter and slightly 

 more in length, some few are larger, while some are not 

 more than '5 mm. in diameter, and of corresponding 

 length. Growth has ceased and the winter rest 

 commenced. 



It is probable that just before the cessation of growth 

 the archesporium is differentiated, but of this I have no 

 evidence, as up to the present I have been unable to 

 discover any trace of this cell. 



Coulter and Chamberlain quote Strasburger as having 

 demonstrated for Larix that the archesporium is 

 differentiated very early in one or more hypodermal cells, 

 and that Thuja, Pinus sylvestris, and P. Pumilio are 

 essentially similar. These authors, while admitting that 

 the probabilities are largely in favour of this statement, 

 make it quite clear that they have been unable to sub- 

 stantiate it. Whatever its origin, it is evidently difficult 

 to distinguish, and but for some fortunately oriented 

 section might be quite easily overlooked. 



About the second or third week of March in the 

 following year, awakened into activity by the genial 

 spring-time warmth, cell-division and consequent growth 

 are renewed, and the numerous protective bud-scales begin 

 to open. 



The history of the development of the microspores is 

 now so well known that a brief sketch of events will 

 suffice. The microsporangia, as we have already noted, 

 went to rest for the winter packed with spore-mother-cells. 

 About the second week in April these mother-cells are 



