106 Scientific Intelligence. 
ilies, stand as veritable exceptions to the universality of the law ¥ 
Darwin has ably deduced. 
What causes the pollen-grains to emit their tubes without contact 
the stigma, and indeed at a considerable distance from it, is an ul 
mystery. Mohl remarks here an analogy with the case of Asclepius, 
that in Viola, Specularia, &e., as Brown has stated for Aaclepias, thet 
is no liquid poured out by the stigma which might somehow place 
pollen in relation with the stigma. 
Finally, Mohl calls attention to an early remark of Linnzeus, that! 
the year 1753, a considerable number of plants raised in the 
den, for which the Sweedish climate was too cool, flowered clandestin 
yet produced fruit. We may note tbat in the Cambridge Botanic Ga 
den, Oxybaphus nyctagineus copiously fruits from the bud in cool al 
cloudy weather: so do one or two Pavonias for a considerable part of 
produced earlier in the season, as in Specularia, Impatiens, &c., but 
times later than the normal blossoms, as in Ozalis and Viola. 
shows that the former conform (he looking upon such flowers as pre 
derantly female) to Knight’s hypothesis, (drawn from cucumbers 
gation upon the production of sexes in the animal kingdom 
has appended to the French translation of Mobl’s paper, an important 
; 
: 
: 
: 
z 
: 
of the Genus Najas, by essor Braun of Berl 
on Hunajas three species are assigned, viz. WV. major, All 
