On tlie Prothallium of Phylloglossn.ni. 289 



and recent writers, as Vines, Bower, Campbell, Goebel, Pritzel,* 

 distinctly state that the development of Phylloglossum is not known. 

 I have not had access to Crie"s original account, and Bertrand,t who 

 quotes Crib's statements, was unable to obtain a germination of the 

 spores during six years' experiments. But in any case it is clear that 

 Crie"s account was incomplete, for the prothallium becomes green, and 

 even vividly green. According to Bertram!, Crie can only have 

 seen the tubercle which precedes the prothallium proper. 



It is not improbable that the prothallium may start life as a sapro- 

 phyte, aided by the endophytic fungus, and I have found a young 

 prothallium which was quite colourless save for a faint yellow tinge at 

 the upper end, as well as two others, still without sexual organs, 

 which showed only scanty chloroplasts. It is quite probable that on 

 the germination of the spore the tubercle is first formed, and when 

 this is at too great a depth in the soil to receive any light, it will 

 doubtless be colourless. But I have never observed any fully de 

 veloped prothallium that was not green above, whilst all prothallia 

 which had succeeded in producing an embryo had reached the surface 

 and attained a considerable development of chlorophyll. 



A comparison of the prothallium of Phylloglossum with those of the 

 few species of Lycopodium in which the gametophyte is known, shows 

 that it is distinctly of a Lycopod type. But, as is well known, there 

 is a remarkable diversity amongst the prothallia of the different 

 species of Lycopodium. On the whole the prothallium of Phyllo- 

 glossum probably resembles a prothallium of the L. cernuum type more 

 closely than any other, though it is quite without the leaf-like assimi- 

 latory lobes of L. cernuum. Perhaps we are justified in regarding it 

 as the simplest known type amongst the Isosporous Lycopodinae. 



The general simplicity of the structure of the prothallium of Phyllo- 

 glossum seems to favour the view that it is a primitive form of 

 Lycopod. It is of course recognised that Phylloglossum is a perma- 

 nently embryonic form, but the simplicity of structure of the mature 

 sporophyte does not necessarily prove that it is a primitive form of 

 the Lycopodiaceous phylum. Bower has expressed the view that 

 Phylloglossum is probably a reduced form, and the absence of transi- 

 tions between the simple cylindrical pointed protophylls and the scale- 

 like sporophylls so like those of some species of Lycopodium may 

 favour this view, if we regard these structures as homologous. Some 

 observations which appear to be new may throw some light upon this 

 question. Bower states that Phylloglossum has been seen branched. 

 I am able to say that branching occurs in at least two distinct 

 ways : 



* E.g., Goebel, ' Organographie der Pflanzen, 2te Toil, 1900," p. 439. Pritzel 

 in Engler and Prantl 'Die Naturlichen Pflanzen-familieu,' Lief. 205 (1900), p. 575. 

 t ' Archives Botaniques du Nord de la France/ 1886, p. 221. 



