DISCOVERY OF MARQUIS WHEAT 219 



no more possible for an unfertilized wheat egg to develop 

 into a wheat plant, or an oak egg to develop into an oak- 

 tree, than it is for an unfertilized fowl's egg to develop 

 into a chicken, or an unfertilized human egg into a child. 

 That plants and animals alike spring from fertilized eggs 

 is one of the most fundamentally important and wonderful 

 of all biological discoveries. 



Exactly how the egg which gave rise in succeeding gen- 

 erations to the plants from which Marquis was selected, 

 came to be fertilized is for us a matter of no little interest, 

 and an elucidation of it will now be attempted. There- 

 after we shall discuss the influence of the parents of Mar- 

 quis upon their off-spring. 



The original kernel from which all the Marquis plants 

 in the world have been derived, came into existence, as we 

 have seen, from an artificial cross between Eed Fife and 

 Hard Red Calcutta. Pollen dust from some stamens re- 

 moved with forceps from a few flowers of the former va- 

 riety, was placed on the two feathery stigmas of a flower 

 of the latter variety. The pollen grains germinated, each 

 grain producing a single pollen tube. The pollen tubes, 

 which were exceedingly delicate cylindrical structures, 

 grew down the stigmas and made their way, by elongating 

 at their apices, into the ovary below. This ovary was a 

 tiny chamber containing a single ovule or potential seed 

 attached laterally to its wall. One of the pollen tubes, 

 guided by chemotropic stimuli, directed its course toward 

 the ovule, entered it at its mouth or micropyle, and pene- 

 trated into its interior as far as the ovum or egg-cell. 

 The egg-cell having been reached, the wall at the tip of the 

 pollen tube liquefied and broke down, and from the open- 

 ing so produced there were emitted two exceedingly minute 

 dense rounded masses of gelatinous protoplasm known as 

 male nuclei. One of these nuclei, carried by forces as yet 



