1917] DUPLER—TAXUS CANADENSIS 131 
Time relations 
The time periods involved in the reproductive process are 
always of interest in the gymnosperms, as use is made of this 
feature in determining the primitive or modern character of a group, 
those having short periods being regarded as the more advanced 
in this respect. In my material the time from microspore formation 
to pollination was about 6.5 months; from pollination to fertiliza- 
tion may be as short as one month, although fertilization generally 
occurs after a longer interval, the time between pollination and 
fertilization having a considerable range, with an accompanying ~ 
range in the time of the maturity of the seed. I have collected 
mature seeds from the first week of July until late in September in 
central Pennsylvania. BELAJEFF (3) shows a pollen tube of 
Taxus baccata with two nuclei collected April 10 and a figure of 
fertilization dated May 26. JAGER (6), at Zurich, reports pollina- 
tion at the beginning or middle of March and fertilization at the 
end of May or beginning of June. Miss Ropertson (18) reports 
the time for fertilization at Kew to be about the middle of June. 
STRASBURGER (4) speaks of fertilization taking place the first half of 
July and the embryo complete by the end of August. None of 
these accounts gives so short a time period as l have found for 
T. canadensis. 
Summary 
Micissbor foceiation takes place i in the autumn. "There are no 
indications of prothallial cells. The pollen grain is uninucleate : 
when shed. 
a on wnt) Pan, ‘ <i. 11. : * 41. 7 ny) pao 
: excessively about the female gametophyte. 
_ Three divisions take place in the ee of the oe : 
ere _ The : body cell divides into two ip eran male cells, a 
"Several megaspore mother cells are fo of which only ome 
ually functions, although “two of them may —- saspores. 
