1910] The Ottawa Naturalist. 221 



extra spikelet and sometimes even less, but the distance between 

 the spikelets is greatly increased while the kernel is Hkely to be 

 starchy, hence environment vrs. quality of grain. Selecting these 

 heads is therefore a useless practice and is always discouraged. 



Physiological Correlations: Under this clags of correlations 

 belong those variations which occur in the functional organs of 

 the plant. An example of this class is given b}^ certain breeders 

 who have noticed that excessive leaf development is followed 

 by a corresponding reduction in the production of seeds. 

 Potatoes, pease and other crops have also demonstrated that 

 an excessive growth of vine or stalk is usually associated with 

 a decreased yield of tubers or seed as the case may be. East 

 discusses this under the heading of "The interrelation of parts 

 not homologous," or "The compensation in growth of plants." 

 This latter law was propounded almost simultaneously many 

 years ago by G. St. Hilaire and Goethe. 



Coherital Correlations: Under this heading are included 

 those characters which seem to be inherited as a single unite 

 character. They are related in such a way that they are 

 "inherited together," although there is little or no evidence to 

 show that this relationship is of any functional importance. 



Webber cites an interesting case of coherital correlation 

 which came to his notice in connection with an attempt to cross 

 Black Mexican and Stowell's Evergreen Sweet corn with a view 

 to producing a hybrid having the tenderness and sweetness of 

 the Mexican but with the larger and more suitable ear for cann- 

 ing purposes peculiar to the Stowells. It was also desired to 

 produce a hybrid having the light colored kernel of the Stowells 

 when in the milk stage with a light blue color indicating "some- 

 thing new" when ripe. In the fourth generation an examination 

 was made and careful notes taken on the color of the silks, 

 stamens and glumes of the tassels. In the pure Mexican these 

 parts are light in color while in the Stowells which produces a 

 white kernel, these organs vary from dark reddish-purple to 

 a lighter pink. It will be noted here that, contrary to w-hat 

 would naturallv be expected, the black kernel produces light 

 colored reproductive organs while the white kernelled variety 

 bears organs which are dark in color. We often find the same 

 peculiarity in wheat. 



An examination of the ears produced in the fourth and 

 fifth generations showed that these related characters still cling 

 together despite the claims of some authorities, notably, 

 johannsen, that hybridization breaks correlations Webber 

 found that only in about one case out of 50 or 100 was the corre- 

 lation broken through hybridization. 



