PICKETT: A STUDY OF CHEILANTHES GRACILLIMA 397 
Even young plants show much more ready branching, leading to 
the formation of plural growing areas, than is usual, as shown by 
Fics. 17, 18, 19, 20, 21, 22 and 23. The plants in Fic. 22 had 
been injured before the two outgrowths were formed, that in 
IG. 23 was grown under normal conditions on the surface of a 
culture solution. 
Another peculiar type of proliferation was observed. In old 
archegonial prothallia grown without the possibility of fertiliz- 
ation, marginal cells in the sinus showed the unusual size and 
arrangement illustrated in Fic. 24. This, as well as some other 
Fics. 26-28. Marginal proliferation of old prothallia. Fics. 29-33. 
Cellular details of marginal growths; the small numbers on Fic. 28 show the 
position of Fics. 29-31. 
peculiar structures on old archegonial prothallia, suggests a type 
of apogamous embryo development; but no embryo that could 
be definitely assigned to apogamous origin has as yet been 
observed in this speci 
These outgrowths in general behave as normal prothallia, 
producing rhizoids, antheridia and archegonia. As might > 
expected, the monosexual character of the old prothallia is 
carried into these outgrowths. The formation of marginal 
