THE AMERICAN BOTANIST. 117 
Style and Stigma in Pollination.— There is prob- 
ably no student of flowers that does not know, in a general 
way, what offices are performed by the st} le and stigma pre- 
liminary to fertilization, but many may not be aware of the 
exact nature of these offices. When the pollen falls upon 
the stigma it begins to germinate and gives rise to a stnic- 
ture called the pollen tube that pushes down through the 
style to the ovules. But pollen tubes cannot be built with- 
out nourishment and therefore the interior of the st>de 
consists of a nutritive tissue upon which the pollen tube can 
draw. The stigma is really the point at which this nutritive 
tissue comes to the surface and this accounts for the fact 
that the stigmatic surface is not always at the apex of the 
style. In some long styles the interior is hollow but lineci 
with nutritive tissue. In cases where a single style serves 
for a several celled ovary a branch of the nutritive tissue 
is given off to each compartment. 
The Interpretation of Species. — At present there 
are no unvarjang rules for distinguishing new species. 
Whenever a student discovers an unrecorded difference be- 
tween two plants he is at liberty to consider the difference 
specific if it appears so to him. At the same time, we are all 
aware that what may appear specific differences to one may 
not to another. Real specific differences, however, are not 
matters of individual opinion or judgment, but are more 
fundamental. By the long and tedious investigation of em- 
bryonic structures we ma}- at last find just how much of 
a plant's character is due to its environment and how much 
is due to something deeper. When specific lines are finally 
drawn in this manner the botanist who has ba^ed a lot of 
new species upon mere fuzziness of leaves, color of flowers 
or size of fruits will be a surprised and disappointed indi- 
