PicKETT: A sTUDY OF CHEILANTHES GRACILLIMA 331 
425-600 uw. in greatest diameter. The exine is very hard and 
brittle. Slight crushing under a coverglass regularly results in 
such fractures as shown in Fics. 2, 3 and 4, and the germination 
of well-matured spores results in the same type of irregular 
fracture. Spores which are immature, as shown by their light 
color and thinner exine, may produce normal plants, but the 
germination of such spores usually results in the separation of 
exine-segments along the sutures. The spores are uninjured by 
Fic. 1. A normal mature spore. Fics. 2-4. Spores showing typical 
fracture of the exine under pressure. Fics. 5-8. Young sporelings showing 
istribution of oil-globules, O, and chloroplasts. Fics. 9, 10. Unusually 
filamentous forms of antheridial plants, the second having developed under 
water. Fic. 11. A normally developing archegonial plant showing unusual 
symmetry, 
desiccating influences. Fronds placed in desiccators over an- 
ydrous calcium chloride in November, 1921, remained there 
until March, 1923, and then furnished spores nearly all of which 
were capable of germination. A number of interesting questions 
enter at this point. It is not desirable to take them up in detail 
at this time; but for other investiagtors who may wish to know 
more of details it should be said that the desiccators used were 
