1908] BURLINGAME—PODOCARPUS 165 



of a longitudinal section somewhat to one side of the middle, and 

 will give an idea of the side view, as well as the relation of the sporan- 

 gial cavity to the sterile portion of the leaf. Fig. 6 shows a cross- 

 section of a sporophyll near the middle of the sporangium. The 

 sporangia are somewhat less prominently exposed on the under side 

 than those of Pinus, for example. A single weakly defined vascular 

 bundle (fig. 6) traverses the upper part of the central sterile septum 

 and is sometimes accompanied by a resin canal lying below it and 

 between the sporangia. The wall of the sporangium varies in thick- 

 ness somewhat, but in general on the freely exposed part it is about 

 four or five cells thick (fig. 5). One or two of the inner layers are 

 slightly differentiated as a tapetum. This is not very evident and 

 does not occur until the sporogenous tissue has nearly reached the 

 mother cell stage. The tapetum does not long persist, but disap- 

 pears as a functional tissue about the time the young spores have 

 formed a thick wall and wings. All of the wall proper, except the 

 outermost layer of thickened cells, may break down before the spores 

 are shed. 



The earliest stages of the sporogenous tissue observed (in P. sp.) 

 lacked one or two divisions of the mother cell stage. Fig. 7 will serve 

 as a typical representative cell of the sporogenous tissue at this stage. 

 The walls are thin and delicate, as is usually the case, and the cyto- 

 plasm stains somewhat more densely than that of the wall cells. It 

 was possible to secure very good preparations of this, considering 

 the nature of the killing and fixing agent. The cells were slightly 

 shrunken, so as to have pulled away in many places from one another 

 or from their own Avails. Fig. 7 will show the principal facts. The 

 cytoplasm does not seem to present either a typically reticulated or 

 a foam structure, but rather resembles a sort of flocculent precip- 

 itate scattered more or less irregularly through the cell. These floc- 

 culent masses may assume a sort of feathery, filamentous, more or 

 less branched form, or they may appear as scattered masses of irregu- 

 lar shape. The filaments and other masses do not seem to be con- 

 nected in any definite manner, but to be distributed through the cell 

 by chance. No stored food can be detected microscopically in the 

 cytoplasm at this time, though the parenchymatous cells of the axial 

 portion of the strobilus contain considerable quantities of large 



