[From the BuLLeTIN oF THE TorREY BoTANIcaL CLUE 33: 327-342, p/. 16, 77. 1906] 
The pollen-tube in some of the Cucurbitaceae * 
Jos—EPpH Epwarp KIRKWooD 
(WITH PLATES 16 AND 17) 
In a previous paper on the embryology of the Cucurbitaceae “* 
it was the writer’s intention to deal with the matters suggested in 
the present title, but lack of evidence on certain points, and other 
Causes, necessitated their omission at that time. It is hoped here 
to discover some of the controlling factors in the behavior of the 
pollen-tube in Melothria, Micrampelis and Cyclanthera, one species 
of each, 
The various phases of the development of the pollen-tube have 
been studied by numerous writers in widely differing subjects, but 
until recently little has been done to determine the nature of the 
influence which directs the pollen-tube in its growth. The con- 
clusions, however, based upon anatomical and experimental evi- 
dence, have been by no means unanimous, and much still remains 
to be done in this field of investigation. 
The behavior of the pollen-tube has been seen to vary considera- 
bly in different groups. The manner in which it approaches the 
embryo-sac in different cases has led Pirotta and Longo” to rec- 
ognize three distinct conditions : acrogamy, in which the pollen- 
tube enters the micropyle, a condition obtaining in the majority of 
seed plants ; basigamy, including those cases in which the tube 
snters by way of the chalaza, occurring in the Amentiferae ; and 
mesogamy, which thus far has been found in a few cases only and 
3 “Pplies to those instances in which the tube enters the nucellus by 
‘ * * eter eeneaeaenimiineeacnmieie mea . 
law This work was done on a research scholarship at the New York Botanical Gar 
Re in the summer of 1904. The writer desires to acknowledge with thanks the kind- 
and coSperation of the officials of that institution. 
327 
