22 BOTANICAL GAZETTE [JULY 
center outward. fig. 57 represents the whole tip of a pro- ¢ 
thallium at the same stage as in fig. 56. Mlle. Sokolowa | 
describes the nucleus of the open prothallial tube as remaining 
at the inner end during its growth toward the center, but after 
the formation of the closing walls the nucleus again moves back 
to near the periphery of the cell. From jig. 54 we see that the 
first statement is true in Taxodium, at least during the very 
young stages. Good preparations were not obtained by me in 
older prothallial tubes before the closure. From Mlle. Soko- 
lowa’s figure of Juniperus, it seems that the mother-cells of the 
archegonia behave in this respect just as the other cells of the 
prothallium, and this is probably true in Taxodium also. 
The prothallial formation in the lower part of the spore does 
not appear to me to be different in essentials from its formation 
above. It is only in the late development of cell walls, and not ‘ 
in their peculiar origin, that the difference consists. The lower al 
part, even after the formation of cell walls, continues to increase 
in size long after the upper part has ceased to grow. In the 
ripe seed the upper end of the nucellus is no larger than at the 
time of fertilization, while the lower part increases greatly in 
size, the whole prothallium acquiring the shape of a slightly 
bent club. After a certain number of cell walls are formed in 
the prothallial tubes, nuclear divisions occur without the forma- 
tion of cell walls, and there arises a multinucleate condition 
(figs. 58, 59). These nuclear divisions are generally, at least, 
of the mitotic type. Jager (’99) describes a fusion of nuclei 
in the prothallial cells of Taxus, but I have not found the 
number of nuclei appreciably smaller in Taxodium even after the 
formation of the embryo. 
DEVELOPMENT OF THE ARCHEGONIA. 
The archegonia of Taxodium are disposed exactly as in the 
Cupresseae. They form a compact group at the base of a com- 
mon depression in the center of the tip of the prothallium. 
Among the many hundred prothallia sectioned only three or 
four were found in which any variation in this arrangement 
occurred. In these exceptional cases there were several smaller - 
