THE LIBRARY. 71 



something at the bottom of all the problems which he 

 proposes to himself to solve that is inherent to his own 

 personal imperfection. He does not know the connection 

 of the subjective and objective ideas; and in his laudable 

 endeavour to obtain possession of the truth he encounters 

 obstacles which he cannot remove, and which it is not 

 given him to interpenetrate and fill. 



' It became possible, after a lapse of centuries, and con- 

 tinued observation, to discover the existence of sexes in 

 plants. The middle ages having passed a dark night of 

 human intelligence, Camerer wrote his famous letter in 

 1694, in which he declares that the anther is the funda- 

 mental portion of the flower ; and somewhat later, on the 

 10th of July, 1717, Vaillant delivered an erudite discourse 

 rejecting the hypothesis of Samuel Morland, and affirming 

 that " the stamens trans wit to the ovules not the grains 

 of pollen but the vapour or volatile spirit, which is emitted 

 by them ; :> and J. B. Amici examines the Portulaca oleracca 

 (a species of the Purslane), and opens to science, with 

 his description of the pollen tube, a wide field for investiga- 

 tion, in which there distinguished themselves Broigniart, 

 Schleiden, Fritzsche, Mohl, Hofmeister, Radlkofer, 

 Schaeht, and many other distinguished naturalists. Let us 

 study the progress of fecundation ; let even the different 

 speed with which the pollen tube advances from its 

 formation be determined ; let it be followed, and be seen to 

 penetrate the microphile, in which it shows a remarkable 

 incisory force and this having been done, when the 

 triumph seems complete arid the phenomena explained, 

 there presents itself the insuperable difficulty of ascertaining 

 what may be the action of the extremity of the pollen 

 tube upon the embryotic vesicle, from which it is kept 

 apart by a membrane which is not perceptibly modified, 

 and the basis being awanting we begin to diverge into the 

 dangerous field of hypothesis ingenious, no doubt, but it 

 may be far from correct, 



