392 



Transactions. 



paper I have not been able to determine satisfactorily. As with the 

 antheridium, the archegonium projects strongly from the surface, practically 

 only the venter being sunk. 



FiG. 18. — Transverse section of a large antheridium, showing the main divisions. 



X 250. 

 Fig. 19. — -The same antheridium as in fig. 18, showing the opercular cell. X 250. 

 Fig. 20. — Longitudinal section of a stout apex of a prothallus, showing two 



young archegonia but not the apical cell. X 75. 

 Fig. 21. — Longitudinal section of a medium-aged archegonium. X 170. 



Adventitious Prothallial Buds. 



Three instances of portions of old prothalli bearing small adventitious 

 buds were noticed. On one of these three young buds had been formed, 

 these being shown in longitudinal section in figs. 22 to 24. Fig. 24 

 shows the actual apex of the bud marked X in fig. 23. from which it is 

 clear that there is a single apical cell. On another fragment of an old 

 prothallus three buds in different stages of development were found, one 

 (fig. 25) being quite young, and the other two (figs. 26. 27) much older. 

 The two latter became detached from the prothallus. Sexual organs were 

 present on both these fragments, so that their prothallial nature is beyond 

 question. The buds were in every case packed with starch, and fungal 

 coils were present in the prothallial cells which immediately adjoined them. 

 The buds arise from the superficial cell-layer of the prothallus. but it is 

 not quite clear whether one or two of these cells are concerned in their 

 formation. The sections shown in figs. 22 and 23 make it appear that the 



