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THE AMERICAN NATURALIST [Vol. XL V 



danviniamtm are periclinal chinneras. This is true also 

 of Cytisus Adami and the Cratcego-mespilus hybrids. 

 Thus 8. tubing ense has its epidermal region derived 

 from the tomato while the inner tissues including those 

 which give rise to the sporogenous cells are of night- 

 shade origin. In 8. proteus the reverse is the case. 

 This explains all cases of reversion to the parent forms 

 and also the character of the seedlings which in the one 

 case are pure nightshade and in the other tomato, this 

 being due to the fact that the spores (pollen spores and 

 embryo-sacs) arise from sub-epidermal tissues derived 

 from the nightshade or the tomato as the case may be. 



These remarkable experiments of Winkler's must be 

 of the greatest interest to all students of the problems 

 of heredity. They emphasize a fact, too often over- 

 looked, that it is not always safe to apply to the study of 

 plants the data of zoology. It must be remembered that 

 in the evolution of the higher plants there has been a 

 constant tendency toward a reduction of the sexual re- 

 productive parts. Many biologists quite ignore the fact 

 that the flowering plant, as it is generally understood, 

 is a purely sexless organism. The so-called sex organs, 

 stamens and carpels, are not such at all, but are non- 

 sexual sporophylls. 



The sexual generation of the highest seed plant is a 

 far simpler organism than that of the moss or fern and 

 the sex organs are correspondingly simpler. Moreover 

 the development of the sex cells and the extraordinary 

 correspondences in nuclear structure, the reduction 

 divisions and the mechanics of fertilization must have 

 developed quite independently of these phenomena in 

 animal cells, since the two great divisions of organisms, 

 plants and animals, parted company for good long be- 

 fore the elaborate structures found in the higher mem- 

 bers of the two series were developed. Hence it by no 



With the subordination of the sexual generation of 



