1907] YOUNG— MALE GAMETOPHYTE OF DACRYDIUM loi 



It was killed and preserved in 70 per cent, alcohol and formalin, 

 imbedded in paraffin, cut 5 yx, and stained part in o. 5 percent, hema- 

 toxylin and orange G and part in safranin and gentian violet. The 

 material consisted of staminate strobili of Dacrydium hijormc, D. 

 BidwilHij D. cupressimintj and D. laxifoHum, and young ovules of 

 D. cupressinum, D. laxijolhim, and D. intermedium. Unfortunately, 



I* 



it was impossible to obtain a complete series from any one species. 

 The first named was in the microspore stage only; the second fur- 

 nished a scries from the microspore up to the shedding of the pollen; 

 the pollen of the third was ready to be shed, but no grains were found 

 in the ovules; the fourth showed young tubes in the micropyles,.and 

 in D. intermedium they had penetrated the nucellus. 



The staminate strobili are 2 to 6"^"^ in length and terminate short 

 branches. The nucleus of the microspore is large and lies near the 

 base of the spore, that is, the side opposite the wings {fig. i). The 

 first division cuts off a lenticular prothallial cell which lies close against 

 the basal wall {fig. 2). Another division soon follows, cutting off from 

 the main body of the spore a second prothallial cell, similar to the 

 first and overlying it {figs, j, 4). Both these cells have distinct though 

 very delicate w^alls; their nuclei are somewhat flattened and stain 

 very deeply, but they show no sign of degeneration; the cytoplasm 

 also is very dense. 



In Dacr}dium, as in Podocarpus and the Abictineae, a third cell 

 is now cut off from the main body of the spore {fig. 5). It overlies 

 the others and is so similar to them that but for its subsequent behavior 

 one might think it a third prothallial cell. It is a generative cell — 

 generative in the sense that it is the ancestor of sperms. This and 

 the second prothallial cell now both divide; usually the division of 

 the latter occurs first, but the order may be reversed {figs. 6, 7). In 

 either case the result is a complex of five distinct cells, one in the 

 lowest, and two in each of the upper tiers, filling about one-third of 

 the cavity of the spore. All the fiv^e nuclei are oval and stain very 

 deeply. The free nucleus, which is now the tube nucleus, divides 

 no more. It is somewhat irregular in outline and is larger and less 

 dense than any of the others. The cytoplasm of the pollen grains is 

 at this time considerably vacuolated. 



Up to this point all the stages described were obtained from Z). 



