308 



MORPHOLOGY. 



ize the embryo which pushes its way into the endosperm from which it 

 derives its food (fig. 362). 



626. Homology of the parts of the female cone. Opinions are divided as 

 to the homology of the parts of the female cone of the pine. Some consider 

 the entire cone to be homologous with a flower of the angiosperms. The 



Fig. 361- 



Archegonium of white pine at stage of fertilization, en, egg nucleus; spn, sperm 

 nucleus in conjugation with it; no, nutritive bodies in cytoplasm of large egg; 

 cpt, cavity of pollen tube; vn, vegetative nucleus or tube nucleus; sc, stalk cell; 

 spn, second sperm nucleus: pr, portion of prothallium or endosperm; sg, starch 

 grains in pollen tube. The sheath of jacket cells of the archegonium is not shown. 

 (After Ferguson.) 



entire scale according to this view is a carpel, or sporophyll, which is divided 

 into the cover scale and the ovuliferous scale. This division of the sporo- 

 phyll is considered similar to that which we have in isoetes, where the spo- 

 rophyll has a ligule above the sporangium, or as in ophioglossum, where the 

 leaf is divided into a fertile and a sterile portion. 



Others believe that the ovuliferous scale is composed of two leaves situ- 

 ated laterally and consolidated representing a shoot in the axis of the bract. 

 There is some support for this in the fact that in certain abnormal cones 

 which show proliferation a short axis appears in the axil of the bract and 



