Edgerley. — Prothallia of Three New Zealand Lycopods. 



95 



examined, ihey are usually _/-^ 

 subterranean, being buried I v/ 



■I -i • it ,1 p r vy 



1 1 



4 2 



in. below the surface of 



an inch or two in thickness. They are filamentous, and ramify beneath 

 the surface of the humus. Usually the young plants are found in colonies, 

 and, by tracing them down from young to younger still, one can obtain 

 those which are still attached to prothallia. 



In the case of L. Billardieri, and also of L. Billardieri var. novae- 

 zelandicum Colenso, spores were sown in humus in which the mature 

 sporophytes had been found growing. These spores were sown in April, 

 but up till November showed no signs of germination. 



The prothallia gathered by the writer were fixed in chromo-acetic acid, 

 and serial sections cut. 



Lycopodium volubile. 



External Form. 



The size and external form of the prothallium in L. volubile can be 

 seen from figs. 1 and 2, which represent in natural size two of the prothallia 

 examined. They are usually _^ _, 



V y 



the soil. They appear a dirty- 

 white colour, lighter on the 

 upper surface, which is desti- 

 tute of the long rhizoids which 

 clothe the rest of the pro- 

 thallium ; but the prothallium 

 depicted in fig. 1 contained 

 some chlorophyll in the ridge 

 at the upper right-hand corner, 

 where it had evidently pro- 

 jected above the surface of 

 the soil. 



The prothallia varied some- 

 what in shape, but. in most Figs. 1, 2.— Prothallia of L. volubile. Natural 

 cases the younger ones ex- size, 



amined were more or less FlGS - la > lb -~ frf-thallium represented in fig. 1, 



i i i seen from two different sides, 



conical below, increasing in 



size higher up. Probably in an earlier stage the prothallium forms a 



cylindrical body or primary tubercle, 

 which later expands at right angles 

 to its axis, so that in older prothallia 

 the primary tubercle can be dis- 

 tinguished as a small projection from 

 the lower surface of the mature pro- 

 thallium. 



The outer edge of the upper sur- 

 face is, in most prothallia, surrounded 

 by a ridge, on the inner surface of 

 which the reproductive organs are 

 produced. This ridge does not pass 

 regularly round the whole margin, 

 but is interrupted in places. Thus 

 the upper surface is concave ; and 



possibly this promotes the fertilization of the archegonia, as Lang suggests 



for the parallel case of L. clavatum. 



a. 



Fig. 3. — Prothallia of L. volubile. 

 bearing archegonia. ur, arche- 

 gonia. X 7. 



