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Transactions. 



drawn-out prothallus of L. ramulosum, desci'ibed later. In the case of 

 those prothalli which bore a young phmt the foot could be plainly dis- 

 cerned through the semitransparent prothallial tissues. The prothallus 

 of this species is very short-lived, and decays aAvay after the young plant 

 has developed two, or at the most three, protophylls. 



L. cernuum. 



Treub has fully described this prothallus. There are three regions 

 — viz., the lower primary tubercle, the intermediate shaft, and the 

 crown of lobes (figs. 17-21). In some cases the tubercle is pointed, in 



Figs. 17-21. — Lycopodium cernuum. Cnmplete prothali, with, and without young plants 



attached. 17, 19, and 2 , X 15; 18 and 24, X 18. 

 Fig. 21a. — Lycopodium cernuum. Young plant, showing foot. X 18. 



others rounded, at the lower extremity. I examined a large number 

 of specimens, and noted that the chief variation in them was in the 

 length of the shaft. This is dependent upon the depth of the germinat- 

 ing spore below the surface of the ground, for the crown of lobes is 

 always at the surface. Fig. 17 shows one prothallus with an abnormally 

 long shaft; on the other hand, in fig. 20 it is seen that the shaft is 

 almost absent. The crown in every case is very much lobed, the lobes 

 of some prothalli being slightly greenish, and of others quite colourless. 

 Rhizoids spring out of both the upper part of the tubercle and the lower 



