HYBRIDS OF JTGLANS. 



41 



seen. Although the development of this trichome was not studied par- 

 icularly, the material examined indicated that the sequence of cell-divisions 

 ay be the same as in the same type of trichome in both pure lines, and 

 us It conforms with the sequence in cell-divisions in all of the other types 

 multicellular trichomes in Juglans. Table 17 presents the measure- 

 ments made on the heads of this form of trichome. The average length 

 of the heads is 22.5 ia; diameter, 40.6 /^. 



Pig. 10.— Trichomes of Juglans cali/oinica X J- regia, ¥i. a, awn-shaped trlcbomes ( X 84); 6 to e, 

 disk-shaped trichomes (6 and d, X 800j; o and e, x 535; / and g, long secreting trichomes Ig, x 

 535); 7i, transverse section of head of long secreting trichome of type with more than 4 cells in 

 head ( X 535); i to q, short secreting trichomes; i ( X 800) and.; (x S35), young trichomes; k, tri- 

 chome from region of vein of leaf (x 535); I, trichome from dorsal leaf-surface (X 535); m, longi- 

 tudinal section of short secreting trichome (X 535): n top, trichomes from old leaf (X 535); q, 

 transverse section of head of short secreting trichome (x 830). 



The short secreting trichome is multicellular and consists of a 2-celled 

 stalk and a head of 4 cells placed radially, as in both pure lines. Beyond 

 the first division of the young trichome, which is a transverse one, no stages 



