238 BOTANICAL GAZETTE [ APRIL. 
may have had their origin in three similar to those of Jig. 29. 
But I have succeeded in getting only two such cases as that of 
fig. 29, one in I, echinospora and one in J. Engelmanni, and have 
failed altogether to obtain a tangential view. 
Tangential sections of the leaf at this early stage are almost 
uninterpretable. The face of the leaf is so closely pressed 
against the back of the next younger one that it is quite impos- 
sible in most instances to distinguish the tissues of the two leaves 
or to determine what is a truly tangential section. That shown 
in fig. 32 was such as to admit of certain interpretation. The 
shaded cells occupy the surface of the leaf and clearly corre- 
spond to the group which we have already examined in longi- 
tudinal and transverse sections. It is probable that another cell 
seen in the adjacent section to the left of those figured belongs 
to the same group, making the total number of cells seven. 
It is evident from a comparison of my figs. 26-28 with figs. 
704-106 of Professor Bower’s plates, that the longitudinal 
growth of the leaf base of J. dacustris is much more rapid than 
that of &. echinospora; and his figures though not his text sug- 
gest that the six superficial cells which make up the sporangium 
Anlage are derived from not more than three rows and _ probably 
from but two. If this suggestion be correct, it would bring 
Bower’s and Hofmeister’s accounts, so far as regards longitudinal 
sections, into harmony with each other, and with the foregoing 
account of /. echinospora. 
The young Sporangium, situated as it is on the hollow side of 
the leaf crescent, projects little if at all from the surface. — By its 
rapid growth, however, it soon forms an oval prominence at first 
wider than long, then nearly circular in surface view, and finally 
considerably longer than wide. In its development I have not 
been able to establish ‘any regular order of sequence. Starting 
from such a beginning as figured in fig. 26, it is certain that 
transverse and longitudinal divisions are the first to occur. 
Then periclinal walls appear (fig. 30). The middle cells of the 
Sporangium rudiment are at first most active in dividing, not 
only in respect to surface growth, but in periclinal divisions also- 
