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TEXTBOOK OF PLANT PHYSIOLOGY 



and the internal of another. According to their external appear- 

 ance such chimeras, called "periclinal," show an intermediate 

 character between the two species (Fig. 152, 3), but cytological 

 investigations have shown that the tissues of each component pre- 

 serve the number of chromosomes characteristic of it, as well as 

 other peculiarities; hence, even in this close union, the reciprocal 



<^xr\Y 



Fig. 152. — Black nightshade and tomato chimeras. 1, Leaf of a normal black 



nightshade; 2, leaf of an anticlinal chimera, 3, leaf of a periclinal chimera; 4, leaf 



of the tomato (redrawn from Winkler) . 



effect of the two species that are closely joined by growth is not 

 very great. 



Other types of chimeras have been obtained, and it has been 

 established that some varieties which have been reproduced 

 vegetatively for a long time, for instance Cytisus Adami, many 

 varieties of Perlargonium, some clones of potato, etc., are chimeras 

 with their inner tissues belonging to one plant, and the exterior to 

 another. While the fruits of such chimeras are usually of a mixed 

 nature, the seeds always belong to the plant which forms the inner 

 tissues. Chimeras may be preserved only by means of vegetative 

 propagation. 



