Nov., 1905.] Life History Sunguinaria canadensis. 
381 
of the microspore had enlarged so that the nucleus was forced 
to one side of the cell. Material taken on March 13th showed 
but little change from that taken on the previous date. The 
megasporocyte had enlarged quite a little and seemed to be pre- 
paring to divide (Fig. 4), and a few spindles were observed 
(Fig. (3). The microspores showed no change. 
Material fixed on March 22nd showed that the megasporocyte 
had divided into four megaspores the lowest being the large 
functional one (Fig. 7). The arrangement of the megaspores 
varied considerably. In some cases the transverse walls were 
nearlv parallel forming a row of cells but frequently they were 
verv irregular (Figs. 7, 8). These divisions are interesting in 
that they show a great similarity to the divisions of the micro- 
sporocyte and often result in a nearly typical tetrad (Fig. 8). 
Above the megaspores the rows of parietal cells could be dis- 
tinctly seen (Fig. 7). These varied in number but it is evident 
that considerable division has occurred in the three original 
parietal cells. Vesque (1) states that Papaver orientale has no 
parietal cells. The nuclei of the microspores were divided at 
this time (Fig. 21). Pollen grains taken at later dates did not 
seem to show any further division. It is probable that the gen- 
erative cell does not divide until after the tube has been formed. 
Strasburger (2) however, reports that in Papaver the generative 
nucleus divides in the pollen grain. 
From this time the development of the functional megaspore 
is rather rapid. Material taken on March 28th showed the com- 
])lete eight celled embryo-sac and often the two polar nuclei had 
already fused to form the definitive nucleus (Fig. 9). The 
antipotals are rather large at this stage and each has a single 
nucleus. Material taken on April 10th showed the oosphere 
and definitive nucleus still undivided but the antipodals were 
very large and each contained two nuclei (Fig. 10). This stage 
corresponded with material taken the year before at about the 
same date. The egg then seems to be fertilized about the first 
week in April. Many of the sections show remains of the pollen 
tube which is very prominent (Figs. 10, 11). The svnergids 
seem to disappear early. Remains of one or more of them could 
usually be seen at this stage, lying to one side of the oospore 
and staining very dark (Figs. 10, 11). The early divisions of 
the embryo seem to occur very slowly for it was not until May 
12th that the first division was observed (Fig. 13). This makes 
a remarkably long period of rest for the fertilized egg. In 
material killed May lOth the three celled embryo was found 
(Fig. 14). The divisions of the definitive nucleus had begun in 
early April and by the latter part of that month the endosperm 
had 20 to 30 nuclei. 
