32 BOTANICAL GAZETTE (JANUARY 
carps appeared, and all the younger ones, already in evidence, began 
to blast, although I did not use the spray. Sections of these showed, 
as usual, that the megasporangia were the first to succumb to the 
unfavorable conditions. Sections of the older ones showed a condi- 
tion which I had not seen before, namely that the blasting was much 
more general in the microsporangia, and that in many of the oldest 
sets of microsporangia megaspores were developing (figs. 32-37); 
while in a few microsporangia abortion had proceeded until only one 
microspore, which was 8-16 times larger than the ordinary ones, 
remained (figs. 28, 31). The few remaining sporocarps were carefully 
grown to maturity, and on dissection showed a number of sori con- 
taining two megaspores instead of one, as I had found in all the cases 
thus far noted. That these secondary forms (called secondary 
because of forming at a later date than the original or primary mega- 
spores, and also because of being smaller; jigs. 32-43) were mega- 
spores there could be no doubt. Every distinguishing character 
peculiar to the megaspore was present, such as size, shape, thickness 
of wall, position and shape of nucleus (which is always apical and 
meniscoid), and manner of vacuolation. There could be no doubt 
that these forms, though occurring in microsporangia, were far beyond 
any microspore in special characters; but they still retained some 
undoubted microspore characters; such as an approach to the general 
spherical form, the long axes of the smaller (intermediate) size being 
proportionally shorter than those of the primary megaspores (jigs. 
38-43). So far I have failed to induce germination in any of these 
induced forms. 
A number of the enlarged microspores from this culture were 
sectioned and showed certain characters belonging to megaspores. 
The ordinary microspore nucleus is spherical and central, while that 
of the megaspore is generally meniscoid and apical. It was easy to 
secure transition forms of nuclei among these microspores, which 
ranged from spherical, central ones in the case of the smaller spores, 
through a series of spheroidal, parietally placed nuclei in larger 
spores (jig. 30), until in the largest sizes, which were also more vacuo- 
lated, there was always found a meniscoid nucleus in the apical region 
of the slightly elongated spore (jig. 37). 
The microsporangium represented in jigs. 28, 29 shows several 
