210 BOTANICAL GAZETTE [SEPTEMBER 
tian violet after it is drawn from the nucellus and integuments. 
The male cells stained best in orange G. Haidenhain’s iron-haema- 
toxylin gave good results, as did also gentian violet. 
FLOWERS. 
The earliest stages in the development of the flower were not 
studied. The first collecting was done on February 13, when the 
ovule was found to contain a clearly defined megaspore, and the 
anthers to be in the pollen mother cell stage. By March 25 the 
trees were in full bloom. 
The method by which self-pollination is prevented, at least to a 
large extent, is of interest. When the flower bud first opens, the 
two-parted stigma is found protruding beyond the anthers and is 
ready for pollination (fig. r). About two of the more centrally placed 
flowers in each cluster are somewhat earlier than the others in length- 
ening their flower stalks and filaments and in opening their anthers 
(fig. 2). The first flower to open its anthers has an excellent oppor 
tunity to pollinate the entire cluster. At the same time this flower 
may be prevented from self-pollination only by the pollen from 
some earlier flower having reached its exposed stigma before its own 
anthers were opened. In many instances the stigmas of flowers 
whose anthers were not yet open were found covered with pollen 
grains, some of which had developed tubes. As the time requi ed 
for the pollen tube to complete its growth is from one to three days, 
it is quite evident that these early tubes will have completed the act of 
fertilization in each flower before its own pollen grains have an oppor 
tunity to begin the development of tubes. 
. MICROSPORANGIUM. 
On February 13 the microsporangia were well formed. Most of 
the sporogenous cells of the four chambers were in the spore mother 
cell stage, in which they had evidently passed the winter (fig 3): 
It is of interest to note that at this stage it is impossible to distin- 
guish any definitely organized tapetum, the cells all having the same 
size and shape, and giving the same reaction to stains. Sporangi 
of the same date were found in which the mother cells had passed 
into the synapsis stage (fig. 4); the nucleolus staining red and ibe 
chromatin mass violet. Many of the cells which were function!ng 
