106 



PROPAGATION OF PLANTS. 



Corn,, and closely allied plants, there is one pistil for each, 

 ovule or seed- vessel, and more than one pollen tube would 



be an entirely superfluous 

 production, iience we find 

 only one. in each. If a 

 pistil is destroyed the 

 ovule at. its bjase remains 

 unfertilized, andjio. grain 

 or eed is. produced, and 

 where a few of the pistils 

 are fertilized and the 

 others not, the result on 

 an ear of Corn will resem- 

 ble the one shown in.fig;? 

 ur^45,, the grains on it 

 varying in number with 

 the number of pistils fer- 

 tilized. It is only about 

 sixty years (1823) since 

 PrQf. Amici, an Italian 

 botanist, discovered the 

 pollen . tubes, and this 

 opened a new field for 

 investigation, which was 

 soon occupied by some of 

 the most eminent botan- 

 ists of Europe. Previous 

 to the discovery of Amici, 

 the process by which the 

 ovules were fertilized was 

 unknown. Some vegeta- 

 ble physiologists supposed 

 that the pollen grains 

 passed bodily through the 

 pistils to the ovary an erroneous idea which still pre- 

 vails among certain horticulturists of the present day. 



Fig. 45. IMPERFECTLY FERTILIZED 

 EAR OF COHN. 



