Vol. 34 No 5 
BULLETIN 
OF THE 
TORREY BOTANICAL CLUB 
MAY, 1907 
Some features of qollen-formation in the Cucurbitaceae * 
JosePpH Epwarp KirkwooD 
(WITH PLATES 17-21) 
Studies in the development and differentiation of the anther 
have been frequent in recent years, and in this line we may cite 
the researches of Gager,? Rosenberg,” Merrell,'® and others. In 
all cases the primordium of the stamen appears as a slight eleva- 
tion of the tissue which later becomes outwardly differentiated 
into its characteristic form and inwardly into spores, tapetum, 
—endothecium, etc. Galinski ” found that in certain of the grasses 
(Secale, Triticum) the anther-wall became differentiated into four 
layers, epidermal, fibrous, degenerating, and tapetal, and that the 
_ original pollen-mother-cells may divide several times. In Zostera 
as described by Rosenberg,” the elongated archesporial cells cut 
off from their ends the cells which form the tapetum. But in 
Asclepias,? Silphium,” and a majority of seed-plants, the immediate 
hypodermal layer has been shown to divide by periclinal walls to 
form the primary tapetal and primary sporogenous cells, the latter 
in some cases undergoing repeated divisions. But in the develop- 
the chromosomes have received most attention. — The results of 
qs ris.7 
these numerous studies have been well summed up by Davis,’ and 
Coulter and Chamberlain,’ and space will not be taken here fora 
Similar task. 
— | PE eS a cat ee 
- * Contributions from the Botanical Laboratory of Syracuse University. 1, : 
[The Butiertn for April 1907 (34: 167-220, #7 .10-16) was issued 11 Je 
1907.] 
221 
