38 



HEREDITY AS ILLUSTRATED BY TRICHOMES. 



FiQ. 9.— Trichomes otjuglanx eaUfornica X nigra, Fj: a, awn-shaped trichome from a leaf; 6 to ;/, 

 disk-shaped trichomes ; e to i, some stages in the rtevelopment of long secreting trichomes ; 

 j, transverse section of head of mature long secreting trichome ; k to m, long secreting tri- 

 chomes ;» to r, long secreting trichomes of the type having a head of more than 4 cells; 

 n, longitudinal sections of the head of a single trichome; o to q, views of long secreting tri- 

 chomes ; r, transverse sections of head of long secreting trichomes of different ages ; «, some 

 stages in^the development of short secreting trichomes. (All figures x 536; reduced one- 

 fourth.) 



