THE GAMETOPHYTES OF CALOPOGON 
EULA PACE 
(WITH PLATES VII-IXx) 
Photolith plates 2nd edition a 
This paper reports a continuation of the work on certain orchids — 
begun in 1906. The peculiarities in the development of the mega- 4 
spores, and in the number and origin of the nuclei in the embryo sac . 
found in Cypripedium (14) made it seem desirable to continue the — 
investigation. 4 
The same methods were used as in the work on Cypripedium. — 
The material of Calopogon pulchellus R. Br. was collected near 4 
Chicago in the summer of 1906. The usual chromacetic and alcohol: — 
formalin solutions were carried to the field and the material was — 
killed as collected. The greater part of it has been cut in serial sec- 
tions five to seven microns thick, and stained in safranin and gentian 
violet. 
MEGASPORES 
The ovules are very numerous and even smaller than those of : 
Cypripedium, the mother cell being five to ten microns in diametel. — 
The archesporium does not seem to be differentiated early. Fig. 1 
shows an ovule pretty well advanced, and yet it is not possible to 3 
distinguish an archesporial cell by any difference in staining. The — 
one drawn shows the greatest difference in size in favor of the usual ig 
archesporial cell, but other ovules in the same ovary show the other 
cells of the axial row to be larger; so here also it is probably the cell : 
that is approaching mitosis that is larger. Fig. 2 is taken from 
another ovary in which the ovules are apparently in the same stage 
as in fig. 1. This one suggests a more advanced stage by the broaden” 
ing of the ovule. Yet this may be related to the appearance of more — 
than the one mother cell, for these ovules with two sporogenous cells 
are broader, as will be seen later. The first undoubted archesporiu™ 
seen was in the stage shown in fig. 3. Here the ovule is much larger 
than in the first two figures and the first integument is beginning. In 
this ovary more than half of the ovules were in this stage, the arche- 
sporial cell being large and showing difference in staining reaction 
Botanical Gazette, vol. 48] [x26 
