370 



Wuist: Branched prothallia 



the filament usually gave rise to the expanded portion of the pro- 

 thallium. In both of these cases the branches originated in the 

 third cell of the filament. In Fig. 2, J, the group of cells at the 

 apex between the branches indicate that there will be a continu- 

 ation of the main growth of the prothallium. In Figs. 2, K, and 

 3, L, M, dichotomous branching developed at a slightly later stage 

 after the first divisions of the expanded portion of the prothallia 

 had been formed. Fig. 4, N-Q, show single lateral branches which 

 appear to have originated at about the same period in the de- 

 velopment of the prothallia as the dichotomous branches shown 

 in Figs. 2, K, and 3, L, M. Fig. 5, R, S, shows branches de- 

 veloped from the expanded portions of the prothallia. In Fig. 



Fig. 5. Branched prothallia of Onoclea sensibilis L. R-T, X 125; U, X 75. 



5, R, the branch formed a plate of cells while in Fig. 5, S, it 

 tended to assume a filamentous character. Fig. 5, T, shows 

 another case of dichotomous branching but at a later stage in the 

 development of the prothallium. Here it occurred at the apex of 

 the expanded region of the young prothallium. Fig. 5, U, is 

 unique in that the branch appears to have originated in the first, 

 second and third cells of the filament. 



