134 BOTANICAL GAZETTE [AUGUST 
the sac, though two are certainly in it (jigs. 21, 22), just as in Cypripe- 
dium. Both may divide, though no evidence beyond a late spirem 
or metaphase stage was seen, except in one case (fig. 24), and here the 
usual disintegration was taking place. So in this respect Calopogon 
might be regarded as suggesting what may have taken place in the 
ancestry of Cypripedium, as it passed from the usual tetrad or row of 
three to its present condition. 
Fertilization.—So-called double fertilization is present here as 
in Cypripedium. It will be remembered that NAWwaAscHIN (13) 
reports it lacking in certain tropical orchids, while STRASBURGER (18) 
found it in orchids he investigated. 
SUMMARY 
1. There is usually one sporogenous cell which becomes the mother 
cell. But in many cases two mother cells are found, either contigu- 
ous or with nucellar tissue between. 
2. Four megaspore nuclei are usually formed; occasionally the 
micropylar daughter cells in the second division either never appear 
or are ephemeral. This leaves two megaspore nuclei in the sac. 
But three of these megaspore nuclei disintegrate, the two from the 
micropylar daughter cell and the micropylar one in the sac. 
3. The embryo sac is the usual eight-nucleate kind, developed in 
the usual way. 
4. Pollinia are in massulae in four loculi. Tetrads are in any 
position, but there is no rounding-up of pollen grains. Tube and 
generative nuclei are formed before the pollen escapes. The pollen 
tube shows a tube nucleus and two male nuclei as it enters the ovary: 
5. Double fertilization occurs. 
BAYLoR UNIVERSITY 
Waco, TEexas 
Y 
LITERATURE CITED 
1.. BARNARD, C. H., Recherch les sph Saag 
Jour. Botanique 14: 118-124, 177-188, 206-212. pls. 4, 5. 1900. 
- Briincs, F. H., A study of Tillandsia usnevides. Bot. GAZETTE 38:99 
121. pls. 8, 9. 1905. 
- Bower, F. O., The origin of a land flora 97. 1908. 
- Brown, W. H., The nature of the embryo sac of Peperomia. Bort. GazETIE 
46: 445-460. pls. 31-33. 1908. : 
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