56 



Journal of Agricultural Research 



Vol. XVI, No. 2 



•52 





-S, 15 



wEi^ 



X X X X X X 



=«■ X X X X X X 



M Q 00 00 ■<a- 00 

 t^ O cs ■'^ c< 00 



X 



»r> Tt ro 2" "^ *^ 



W M M '"' M M 



X X X X X X 



i r 



^ § 



CO 



c 



r- O 



Pi Pi ^ 



Pi Pi Pi 



pT Pi" Pi"" 



^ 



