VOLUME XXV NUMBER 4 
BOTANICAL (,AZETTE 
APRIL 1898 
_ PON POLYEMBRYONY AND ITS MORPHOLOGY IN 
OPUNTIA VULGARIS. 
ras W. F. GANONG. re) 
(WITH PLATE XVI) 
a Many cases of polyembryony are now known, occurring in 
. widely Separated groups. Braun, in his summary of the subject 
_ © 1860, recorded twenty-one cases in twelve families and 
thirteen genera, which number has been added to by others. 
Strasburger was the first to thoroughly investigate its morpho- 
on | basis, and since his paper in 1878 important contribu- 
tens have been made to the subject by several investigators, 
trey ly Dodel (1890), Overton (1891), Tretjakow (1895), Jef- 
lee (1895), and Hegelmaier (1897). The results of these 
ks iso far as they touch this subject, will be found sum- 
“a al In the Cactacez, the only case of polyem? 
ce . itherto known has been that of Opuntia ikea apa 
bes hgelmann, in his Cactacee of Whipple’s expedition 
| (el. 23, fig.4) as having two embryos in one seed. This 
Was cited by Braun (p. 155, pl. 5, figs. 18-20), who also 
i * the four cotyledons which he had himself noticed 
hene  Slaucophylla may indicate a fusion of two embryos and 
e Polyembryony, though he points out that it may also be 
kas. fasciation. While studying the seedling stages 1m 
: a » T have found that Opuntia vulgaris is markedly poly- 
1, and J may here add ‘that although I have worked 
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