1 68 Lawson . — The Gametophytes and Embryo of 
Compared with Pinas , Torreya , Cephalotaxns , and certain other Conifers, 
the time required for the complete development of the male gametophyte is 
very short. The sperm nuclei are organized, and fertilization takes place 
within sixty days after pollination. 
The number and history of the nuclear structures which constitute the 
male sexual generation in Psendotsuga are in all essentials similar to those 
of Pinas and Picea, the only two genera of the Abietineae in which a full 
account has been recorded. 
The Female Gametophyte. 
The collection of material was commenced too late to allow of a study 
of the development of the megaspores. In the ovules taken March 30 the 
megaspore was not only fully organized but had already germinated — 
its nucleus having undergone repeated free division. The earliest stage 
found is represented in Fig. 9. It may be seen from this figure that the 
functional megaspore is very much enlarged, and at the micropylar end 
are at least two flattened structures which I interpret as the remains of 
disintegrating functionless spores. These remains were so far disintegrated 
that it was impossible to distinguish a membrane between them. They 
appeared to be two fragmented nuclei. They were, however, separated from 
the functional spore by a definite membrane. It was impossible to say 
whether a fourth spore had been formed. The position of the three observed, 
however, makes it clear that, whether three or four spores are originally 
formed, they are arranged in an axial row. 
The interior of the functional megaspore consisted mainly of cell-sap 
contained within two or three large vacuoles. In proportion to its size 
comparatively little cytoplasm was present, and this was found mainly at the 
periphery and surrounding the free nuclei. Three of the free nuclei are to 
be seen in Fig. 9. The spore wall could be made out as a very thin delicate 
membrane, apparently of a plasmatic nature. 
Completely enveloping the growing megaspore, and in close contact 
with the spore membrane, there is a layer of large sporogenous-like cells. 
These large cells form practically a single layer, although at places, as 
indicated in Fig. 9, they may appear two cells deep. They are at least 
three or four times the size of the ordinary surrounding cells of the nucellus, 
and as their cytoplasm is very highly granular, and their nuclei large and 
deeply staining, the entire layer has the characteristic appearance of 
sporogenous tissue. 
From the fact that these cells are so closely associated with the young 
growing prothallium, and from the fact that they are so fully charged with 
nutritive substances, one can only conclude that they are nutritive in function. 
They constitute an early stage in the formation of the so-called ‘ spongy 
tissue 5 or ‘tapetum’ which has been frequently described for Pinas and other 
