1899] DEVELOPMENT OF THE MICROSPORANGIUM 331 
THE DEVELOPMENT OF THE MICROSPORANGIUM. 
In 1873 Warming’s important work on the development of 
theanther apeared.* In this paper we find for the first time a 
correct description of the succession of cell divisions result- 
ing in the formation of the archesporium and the anther wall. 
| It was not followed up, however, by other investigators, and 
en in late years nothing of importance has been done along 
this line. The most important of the subsequent papers is 
indoubtedly that of Engler in which Orchis is taken up in 
detail, 
Warming established the fact that the archesporium arises 
from the daughter cells resulting from the division of the hypo- 
dermal layer at each corner of the anther. If the hypodermal 
lls form a true layer, then the archesporium will usually also 
tein the form of a layer; but in some cases the hypodermal 
cals may be reduced to one, and the resulting archesporium in 
that case is simply a vertical row of cells. In any event, there is 
most no subsequent division in the archesporium, growth being 
‘onfined entirely to an increase in size of the existing cells. Of 
) 3 Wo original daughter cells of any hypodermal cell, the inner 
Yes tise to the archesporium, the outer to the anther wall. By 
"0 or three periclinal divisions progressing in a centrifugal 
Tanner a radial row of cells is formed, the inner cell of which 
Mes the tapetum, the outer the endothecial layer, and the 
= finally disintegrate. Although many of the divisions are 
a a linal, some are radial and others transverse, by which epee 
fe genmttion is provided for the growth of the archesporium. 
a nds also that cell division in the epidermis is almost entirely 
yd transverse, and this structure remains always one-cell 
“Me oo His subjects for investigation, however, included a 
Aleagl "cotyledon; and Engler,’ who attempted to show mor 
: Y the application of Warming’s laws to the monocotyledons, 
4 
pau ay “9 nt. 
: ti. cL achungen liber pollenbildende Phyllome und Caulome. Hanstein’s Bot 
: te ANd Se 
Beitrag i t. 10: 
Abe age zur Kenntniss der Antherenbildung. Pringsh. Jahrb. f. wiss- Bo 
