82 ON THE PARTS OF A BLOWER NECESSARY 



though to the naked eye a fine powder, arid light enough to be wafted 

 along by the air, is so curiously formed, and so various in different 

 plants, as to be an interesting and popular object for the microscope. 

 Each grain of it is commonly a membranous bag, round or angular, 

 rough or smooth, which remaining entire- till it meets with any 

 moisture (being contrary, in this respect, to the anther), then it 

 bursts with great force, discharging a most subtle vapour. 



It is said that the pollen contains hydrogen gas ; and, being thus 

 rendered specifically lighter than atmospheric air, it floats therein till 

 it lights on the medium which it is prepared to impregnate. If this 

 be the fact, it will be interesting to investigate it as a phenomenon 

 of attraction, and subject to the influence of that law by which bodies 

 in opposite states of electricity tend to form a union one with the 

 other. In this view of the subject, the pollen, it is probable, will 

 never explode, and, consequently, will fail to impregnate the organs 

 of any germen which does not attract it by the agency of a gas or 

 fluid in a specifically opposite state of electricity. But should the 

 dust approach an organ possessing and exerting such a specific energy 

 on the gas contained in the membranous bag, it will burst, and pro- 

 duce a new arrangement of the chemical elements of the embryo seed 

 in the germen. The gaseous theory will throw some light upon the 

 phenomenon of the mixtures and crossings which take place in the 

 cabbage tribe, and among individuals of congenerous species; and, 

 by assuming that specific attractions must take place before any 

 impregnation can be effected, it will evince the utter impossibility of 

 a general and promiscuous fertilisation, which, were it not provided 

 against, would produce the utmost confusion among the genera and 

 species of plants. The theory and the fact bear out each other, and 

 daily experience proves that which the hypothesis presumes. 



Pistilla (from pistillum, a pestle, from the resemblance, doubtless, 

 of the organ to that utensil).— The pistils, or pointals, are not less 

 essential than the stamina ; they stand in the centre of the flower, 

 and usually are fewer in number. Sometimes the pistil is not in the 

 same flower as the stamens, and then it does not always occupy the 

 centre of the flower. Every pistil consists of three parts ; first, the 

 germen — this is essential, as it is the rudiment or matrix of the seed 

 or fruit; second, stylus, the style (from 2rvo£, stulos, a stalk, or 

 sharp-pointed pencil). This part is sometimes wanting, it also 



