12 



HEREDITY AS ILLUSTRATED BY TRICHOMES. 



TRICHOMES OF PAPAVER HYBRIDS AND THE PURE SPECIES. 



TRICHOMES OF THE PURE SPECIES. 



The three species o£ Papaver 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 

 orientale), although they usually are shorter than this. 



Fig. 2.— Tricbomes of Papaver pure lines and hybrids. Papaver somni/erum: a, multicellu- 

 lar trichome from young stem ( x 44); 6, detail of tip of trichome, showing appressed dis- 

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

 projection of distal ends of superficial cells ( X 362); d, detail from middle portion of tri- 

 chome ( X362). Papaver pilosum: e, 2 trichomes, semi-diagrammatic, to illustrate the 

 projection of superficial cells ( X 84). Papaver somni/erum X -P. orientale: /, detail from 

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

 only a portion of which project ( c302); j/, tip of trichome (X362). Papaver somni/erum 

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

 of superficial cells ( X 84). 



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

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

 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 



