148 BOTANICAL GAZETTE | MARCH 
be expected to prove instructive. The perplexing variation in 
‘species, the well known propensity to hybridize, and the fre- 
quency of sports increase the probability of interesting results. 
Finally, Chicago and its environs afford an abundance of 
material representing three-fourths of the species credited to 
the United States. 
At first it was my purpose to examine Salix only with refer- 
erence to chalazogamy and the structures of the embryo sac, but 
as the subject developed it was thought best to extend the scope 
of the work. The subjects discussed are (1) material and meth- 
ods, (2) organogeny of the flower, (3) development of the 
microspores, (4) origin of the macrospore, (5) germination of 
the macrospore, (6) pollen tubes and fertilization, (7) develop- 
ment of the embryo, (8) teratology, (g) Salix and other Amen- 
tifere, (10) summary. 
Complete series from the formation of the archesporium to 
the mature embryo were studied in S. petiolaris and S. glaucophylla. 
Series lacking but few stages were studied in S. ¢vistis, S. discolor 
and S. cordata. Less complete series were studied in twelve 
other species. 
«The investigations were conducted under the guidance of 
Professor John M. Coulter, whose valuable suggestions and kindly 
encouragement are acknowledged with gratitude. 
MATERIAL AND METHODS. 
The greater part of my material was collected at Grand 
Crossing, Illinois, but many gatherings were made from the 
higher ground north of Chicago, and from the sand dune region. 
of northern Indiana. The collecting began February 14, 1895+ 
and ; le at intervals of two or three days until oe 
the latter part of May. A few collections of buds were made in 
the autumn and winter. This furnished | nearly complete series 
in ie glaucophylla, S. cordata, and S. tristis, with many other species” : 
represented by, several stages. During | the following spring gaps 
in the series were filled, a good series of S. petiolaris was col-— 
: lected, and a many monstrous forms were : found. In es -— 
