86 ' VEGETABLE HYBRIDITY. 
with respect to graphite, but .in diamonds I have found nmneroua. 
foreign bodies enclosed, of which if they cannot be said to be evidently 
and nndonbtedly vegetable in their origin^ it would on the other hand 
be difficult to deny their vegetable nature altogether. The careful 
figures which will accompany my essay, will enable otliers to judge on 
this point, and will, if nothing else, open up the way for further re- 
searches. 
VEGETABLE HYBEIDITY. 
M. C, Naudin has recently communicated to the Academy of Sciences 
of Paris some observations on tlie hybridity in plants, which place in a 
striking light the possible variations of which the impregnation of one 
plant by the pollen of another may be the cause. At the same time 
they furnish important data in the discussion of qxiestions connected 
with the origin of species. Thus although hybrid plants, when en- 
dowed with sufficient fertility to propagate their kind beyond the se- 
cond generation, frequently and speedily revert to the type of one or 
the other of the original species, nothing is more common than to find 
that certain individuals not only persist in their divergence from both 
the primary types, but actually depart still more widely from the origi- 
nal parents, and even in some cases present considerable differences- 
from the first generation of hybrids. The elucidation of these curious 
points has been the object of M. Nandin's experiments, of which the: 
results are contained in the memoir of which we propose to furnish our 
readers with an abstract. 
In 1862, M. Naudin experimented with four species of Datura; 
namely,!). Icevis.ferox, Stramonium, and quercifolia, all belonging io a^ 
subgeneric group which maybe divided into two series, in one of which 
the plants have green stems and white flowers, whilst in the other the 
stems are more or less tinged with brown and the flowers violet. D. 
Stramonium, Icevis, and ferox belong to the former, and D. querci/olia, 
with some other species, to the latter. The four species are perfectly 
distinct, and show no tendency to variation. 
The intercrossings, made with all necessary precautions, were very 
successful. They were effected in both directions ; that is to say, the 
