118 BOTANICAL GAZETTE [AUGUST 
17) are binucleate when shed, the microspore having divided 
into the tube and generative cells while in the microsporangium. 
The absence of prothallial cells is a feature common to the Taxineae, 
Taxodineae, and Cupressineae. 
POLLINATION.—In the spring of 1914, in the vicinity of Hunting- 
don, Pennsylvania, pollination was first noted April 23. No 
strobili were found shedding pollen on April 20, but 3 days later 
pollen was being shed abundantly, especially in the more exposed 
situations, and most of the ovules collected at that time contain — 
pollen grains. JAGER (6), at Zurich, reports the beginning or 
middle of March as the time for the pollination of T. baccata. 
The pollen grains are wind scattered and are formed in great 
abundance, while the frequent occurrence of both staminate 
and ovulate strobili on the same shoot increases the chances for 
pollination. In the material which I have examined there were 
very few ovules which had not been pollinated, and sometimes 
quite abundantly, as is evidenced by the frequency of several 
pollen tubes in an ovule. The pollen is caught by the small 
pollination droplet which protrudes from the micropyle of the 
ovule and is drawn into the yeas ey the concentration of the 
- droplet. | - 
Inthe ovule the pollen grains are found 1 sf the . 
— nucellus. While no definite pollen. chamber is ; formed, the outer- : 
‘most cells of the nucellus begin to disintegrate about the time of 
pollination, resulting in a ragged edge to the sonaicae on which the 
_ pollen grains become lodged. a 
POLLEN TUBE.—The pollen grain, oe on the nucellus, soon 
. begins to elongate, the exine is ruptured, and the intine grows | out 
to form the tube. The young tube soon penetr ellus, gO 
: = once started, ‘invades: ‘the tissue very rapidly. ‘Within ae 
te while others ~ not E have » penetrated s so a there being 
