CONIFERALES (TAXACEAE) 



345 



taxus Fortunei (124), and Phyllodadus (144) the functioning male 

 cell, with its complete investment of cytoplasm, has been observed 

 to come in contact with the egg nucleus (ligs. 399, 400). In this 

 position, the male cytoplasm spreads from its own nucleus and invests 

 the egg nucleus, and this investment is very evident in the fusion 

 nucleus, and may persist in Torreya taxijoUa as a distinct cytoplasmic 

 sheath even about the four free nuclei at wall-formation. This 

 sheath is recognizable on 

 account of its abundant 

 supply of food material, 

 and is doubtless of serv- 

 ice in the nutrition of 

 the fusion nucleus. In 

 Cephalotaxiis drupacea 

 (130), in which male cells 

 are not formed, the two 

 free male nuclei do not 

 escape from the mem- 

 brane of the body cell 

 until at the time of dis- 

 charge. 



An interesting conse- 

 quence of the early ap- 

 pearance and fertilization 

 of the eggs of Torreya 

 taxijolia may be men- 

 tioned. At this time the endosperm tissue has not grown, and in its 

 subsequent development it grows about the tip of the pollen tube, 

 incloses the fertilized egg, and forms quite a beak above the embryo. 



Critical observations of fertilization among the conifers are not 

 numerous enough to form the basis of a general conclusion, but the 

 evidence thus far indicates that the behavior of the male cytoplasm, in 

 investing the fusion nucleus as a nutritive zone, is a feature of the 

 Taxaceae; while among the Pinaceae the male nucleus slips from its 

 cytoplasmic sheath in the periphery of the egg cytoplasm (with Taxo- 

 dium and Juniperus as exceptions). Subsequent im-estigation may 

 show that both methods belong indiscriminately to both families. 



Fig. 400. — Phyllodadus alpina: fertilization; 

 both male cells are shown, the one at the right is 

 functional, and the one at the left is disorganizing; 

 X440. — After Miss Young (174). 



