12 



HEREDITY AS ILLUSTRATED BY TRICHOMES. 



TRICHOMES OF PAPAVER HYBRIDS AND THE PURE SPECIES. 



TRICHOMES OF THE PURE SPECIES. 



The three species of Pa paver which were studied have only one type of 

 trichome, which is multicellular, awn-shaped, and usually slightly curved 

 (fig. 2). The trichomes may attain a length so great as 7.0 mm. {Papaver 

 orientate), although they usually are shorter than this. 



Fig. 2. Trichomes of Papaver pure lines and hybrids. Papaver somniferum: a, multicellu- 

 lar trichome from young stem ( 44); b, detail of tip of trichome, showing appressed dis- 

 tal ends of the superficial cells ( x 362). Papaver orientate: c, tip of trichome, to show the 

 projection of distal ends of superficial cells ( 362); (/.detail from middle portion of tri- 

 chome ( 3(52). Papaver pilotsum: e, 2 trichomes, semi-diagrammatic, to illustrate the 

 projection of superficial cells ( 84). Papaver somniferum P. orientate: f, detail from 

 middle part of a typical trichome, to show the inconsistent behavior of superficial cells, 

 only a portion of which project ( <362); g, tip of trichome ( 302). Papaver somniferum 

 X P. pilosum: h and i, trichomes from a leaf, illustrating relatively prominent projections 

 of superficial cells ( < 84). 



The trichomes have a curious structure, unlike any other encountered in 

 the course of this investigation, Their growth appears to be indeteiTnin- 

 ate. As a direct result of this character the length of the trichomes is 

 very unequal, so that comparative study of them from this standpoint would 

 be without value. The trichomes end in a single much-elongated cell 



