iqiq] 



STEIL—PTERIS 



477 



both petiole and lamina of the leaf. The development of the 

 gametophytic portion was observed for several months and during 

 this period grew rapidly. In the meantime the first secondary leaf 

 had been produced. From both surfaces of the prothallium pro- 

 jections appeared, one of which resembled a young sporophyte {s). 

 In this case a root (r) had been produced. The two projections (o) 

 on the same surface of the prothallium (fig. 15) were similar to tho^e 

 appearing on the other surface, which with a small portion of the 

 prothallium are shown 

 highly magnified in 

 fig. 14. While there 

 is no marked differ- 

 ence between the form 

 of the cells of the out- 

 growth and the pro- 

 thallium, those of the 

 latter are much larger. 

 Whether any or all 

 such projections pro- 

 duce embryos was not 

 determined. If the 

 aposporously pro- 

 duced prothallia of 

 Pteris sulcata are like 

 those developed from 

 the germination of a 

 spore, and I am in- 

 clined to think that they are, such growths may produce prothallia, 

 cyUndrical in form, sporophytes normal in every respect, or forms 

 intermediate in character between gametophyte and sporophyte. 

 These were frequently observed to develop from the prothallia in 

 the culture. On the surface of the prothallium, from which the 

 single projection appeared, a number of antheridia had also been 

 formed. The nature of the cells of the two generations is shown in 

 a highly magnified portion of the region between the lamina of the 

 leaf and the prothalloid part id). There is also in this case a sharp 

 line of demarcation between the two generations (fig. 3). 



Fig. 3. — Cells of Pteris stdcala between gametophyte 

 and sporophyte; X170. 



