1916) FORSAITH—ON AGRACEAE 487 
Fic. 9.—E. latifolium L., showing evidences of abortion in a large per- 
centage of the grains; X75. 
1G. 10.—E. latifolium L., showing defective pollen; 150. 
Fic. 11.—E. latifolium L., showing perfect and imperfect pollen; X12 ¢. 
Fic. 12.—E. obcordatum Grey, showing fertile and abortive pollen grains 
in relation to tetrad; X125 
Fic. 13.—Clarkia Yates Gray, showing ee developed pollen 
grains; X 125. 
Fic. 14.—C. Xanthina Gray, showing tertile and infertile pollen; 125. 
Fic. 15.—Oenothera serrulata Nutt., showing relative. size of fertile and 
déeehetnte pollen; X125 
Fic. 16.—Diplandra lopezoides Hook. and Arn., showing functional 
microspores; X 200. 
Fic. 17.—Zauschneria californica Presl., showing no indication of abortion 
in any of tetrads; X50. 
Fic. 18.—Z. californica Presl., showing tetrads in which all grains are 
uniformly developed; X 125. : 
