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Transactions. 



The development of an embryo seems to bring all further growth of 

 the prothallus to an end. The prothallus of this species is generally small 

 and delicate, and does not long persist attached to its young plant. It 

 has in most cases decayed away by the time that the plant has developed 

 two or three protophylls. However, I have several times found prothalli 

 of L. mmulosum still persisting, in one case healthily green in colour, 

 attached to plantlets of seven or eight protophylls. 



The intraprothallial portion of the embryo plant is developed as an 

 absorbing-organ, but only to a slight extent as compared with the same 

 organ in the young plant of the Selago and Phlegmaria types. Still less 

 is it comparable in importance with the large " foot " of the clavatum and 

 complanatum types. This progressive importance of the foot in the dif- 

 ferent types, taken in the order in which they are mentioned, goes hand 



Fig. 72. — L. cernuum. Longitudinal section of prothallus and young plant showing 



foot. X 30. 

 Fig. 73. — L. cernuum. Transverse section of suspensor and foot of young ^ plant. 



X 42. 

 Fig. 74. — L. cernuum. Longitudinal section of foot and part of protocorm of young 



plant. - X 42. 

 Fig. 75. — L. ramulosum. Oblique section of portion of basal fungal region showing 



three large " spore " capsules of undetermined nature, x 250. 



in hand with the increase in the size of the prothalli and of the extent of 

 the dependence of the young plant upon its parent prothallus. From the 

 figures mentioned above it will be seen that the surface cells of the foot 

 in the three species of the cernuum type are only slightly developed as an 

 epithelial layer. They are best iliustrated in fig. 73, which is a transverse 

 section of the foot and suspensor of the young plant of L. cernuum, and 

 fig. 74, which shows the foot in longitudinal section. 



In Part II of these papers (8, p. 92) I stated that I had never observed 

 the presence of fungal hyphae in any of the protocorms which I had examined. 

 This statement I must correct. Th^ fungus is certainly never present as 



