HYBRIDS OF JUG LANS. 



41 



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

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

 may be the same as in the same type of triehome in both pure lines, and 

 thus it conforms with the sequence in cell-divisions in all of the other types 

 of multicellular trichomes in Juglans. Tabic 17 presents the measure- 

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

 of the heads is 22.5 ^; diameter, 40.6 fi. 



Fig. 10. Trichomes of Juglans calif or nica J. regia, F } : , awn-shaped trichomes ( 84); b toe, 

 disk-shaped trichomes (b and rf, SOOj: e and e, 53"); / and g, long secreting trichomes (g, x 

 535); h, transverse section of head of long secreting triehome of type with more than 4 cells in 

 head ( < 535); i to g, short secreting trichomes; i ( 800) and,/' ( 535), young trichomes; /.-, tri- 

 ehome from region of vein of leaf ( .535); I, triehome from dorsal leaf-surface ( X 535); m, longi- 

 tudinal section of short secreting triehome (X 535): n to p, trichomes from old leaf ( 535); g, 

 transverse section of head of short secreting triehome ( 830). 



The short secreting triehome 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 triehome, which is a transverse one, no stages 



