CONIPERALES 



79 



fertilization, which occurs about the 1st of July, at least twenty- 

 one months after the first organization of the ovule. It should 

 also be remembered that after fertilization the seed is not shed 

 until the following year, fully three years 

 after the first appearance of the ovule. 

 Practically the same history was reported 

 by Strasburger ^* in the case of Larix, and 

 it probably represents a common condition 

 among Conifers, a condition which is hard 

 to detect without the greatest care. 



The portion of this long history which 

 concerns us at present ends with the dis- 

 tinct organization of the mother cell, and 

 it is this very period which seems to have 

 received the least attention. There is cur- 

 rent the general statement that the arche- 

 sporium is differentiated very early as one 

 or more hypodermal cells. While the 

 probabilities are largely in favor of the 

 truth of this statement, we have discovered 

 no complete series of figures to substan- 

 tiate it except those of Larix given by 

 Strasburger.^* In the same connection he 

 gives certian figures of Taxus which indi- 

 cate the same fact, and also remarks that 

 Thuja, Pinus silvestris, and Pinus Pu- 

 milio are essentially the same as Larix in this regard. It should 

 be remembered, therefore, that the only close series is from 

 Larix, and that the series is the same in other forms is more 

 or less a matter of inference from fragmentary observations 



(rig. 61). 



A periclinal wall divides each archesporial cell into an outer 

 primary wall cell and an inner primary sporogenous cell. The 

 wall cells divide repeatedly, and as these divisions are accom- 

 panied by division of the overlying epidermal cells an extensive 

 mass of sterile nucellar tissue is developed between the micro- 

 pyle and the sporogenous cells. Moreover, the divisions are so 

 regular that definite rows of sterile cells extend from the sporog- 

 enous tissue to the tip of the nucellus. So far as recorded, the 

 nucellus in Conifers does not develop the persistent beak char- 



Fio. 62. — Pimts Zarido, 

 condition of megaspo- 

 rangium on May 1st : », 

 integument; p, pollen 

 tube ; n, nucellus ; ff, 

 beginning of gameto- 

 phyte, the embryo sao 

 being surrounded by a 

 deiinite region of break- 

 ing down tissue. 



