Botany and Zoology. 69 
striking case was first brought to light. Our Vesa verticillata 
is also referred to, the trimorphous species of Oxalis Aaaee eek, and 
finally Pontederia, the only monocotyledonous genus now known 
to be heterogone. e trimorphism in this genus was dacacie a 
data, our common Pickerel-weed. by Mr. Leggett of New “York. 
Chapter VI is a detailed discussion of experiments on the illegiti- 
mate offspring of heterogone flowers; i. e., offspring produced by 
breeding shea the danse ofthe same ‘form, short-sty ed with long- 
' stamened, or th The conclusion is that in all points 
e con 
“the patallelison | is moudeetals close between the effects of illegit- 
imate and hybrid fertilization. It is hardly an exaggeration to 
assert that seedlings from an Fh ager aay cde fertilized — 
of Lythrum or Primula for the sake of ascertaining whether the 
were specifically distinct, and he found that they could be united 
nly with some di culty, that their offspring were i’ 
whole series of tions crossed species and Lad Ae brid off 
spring, he might maintain that his oe had b roved to 
be good and true species ; but he w be co mpletely deceived.” 
The cause of this sterility between gre iduals w may h 
sprung from the very same parent or parents an from the 
same = must evidently in their 1 e organs 
reproductiv 
n some recondite incompatibility of their sexual ele- 
ments, ase in any general difference of structure or constitution. 
And Mr. Darwin effectively argues that the same holds in ca 
of distinct species of the same genus. “ We are indeed led to 
this same conclusion,” he adds, “ the impossibility of detecting 
any differences sufficient to account for certain species crossing 
with the —— ease, whilst other state allied se cannot 
be crossed, or can be crossed only with extreme di 
are led to this. conclusion euigie more forcibly by causitienie the 
great difference which often exists in the facility of crossing 
reciprocally the same two § sea: or it is manifest in this case 
ility of hybrids ceas es to be a criterion of specie 
The 6th ee follows up the subject in a series of pee penis 
remarks. It refers to those cases of more or less recip 
rocal differences i in stamens and style which are una prt 
any difference in size or form of pollen-grains; and it tabulates 
the difference in pollen-grains of the two sorts. “ With all the 
oe in which the grains differ in diameter, there is no excep- 
to the rule, that those from the anehaee of the short-styled 
* 
