Edgbrley. — Prothallia of Three New Zealand Lycopods. 



99 



10 



nucleolus, and, above, two cells each with a single nucleus ; then a cell con- 

 taining seven nuclei, the lowest four of which are arranged in pairs. The 

 lower part of the archegonium is buried in the tissue of the prothallium, 

 and a layer of tabular cells is cut off round the ovum from the neighbouring 

 prothallial cells. 



The Young Sporophyte. 



Unfortunately, the writer was not able to trace the different stages in 

 the development of the young sporophyte. The prothallia persist for a long 

 time, and may be found still at- 

 tached to a young plant which has 

 reached a height of If in. or 2 in. 

 (fig. 9). It is quite common to 

 find two, or even three, sporo- 

 phytes attached to the same pro- 

 thallium (figs. 10 and 11). As 

 in all species of Lycopodium, the 

 first root appears relatively late, 

 some sporophytes an inch in height 

 showing no trace of it. 



Sections of two embryos were 

 obtained which had not yet broken 

 through the prothallium. The 

 youngest was an oval parenchy- 

 matous mass, whose cells were very 

 rich in starch (fig. 12). The sus- 

 pensor consisted of one or two cells, 

 and the stem and foot were quite 

 undifferentiated. The other (fig. 

 13) was slightly older, and quite 

 spherical, owing to the rapid growth 

 of the cells of the foot segment. 



Fig. 9. — Prothallium of L. volubile, bearing 

 a single sporophyte. s, stem; pr, pro- 

 thallium ; rt, root. Natural size. 



Figs. 10, 11. — Prothallia of L. volubile, 

 bearing two and three young sporophytes 

 respectively. Natural size. 



The cells of the stem tier were rather 



smaller, while the outer limiting layer of the foot consisted of large cells. 



Figs. 12, 13. — Sections of two young embryos of L. volubile. 

 st, stem segment ; ft, foot segment. X 267. 



A section of a basal part of a young sporophyte still attached to!the 

 prothallium revealed the presence of a massive foot, the outer cells of which 

 form an absorptive layer (fig. 14). The cells of this absorptive layer have 

 much-thickened outer and side walls, which stain very deeply with haemalum. 



