106 FETTER: POLYEMBRYONY IN POLYPODIACEOUS FERNS 
In prothallia that have been divided longitudinally, each 
half may be made to grow and to develop two or more embryos. 
In some cases each half may regenerate one or two heart- 
shaped lobes on which an embryo or emibryos may be produced, 
as well as on the original half. 
Parts of quartered prothallia under favorable conditions 
may continue growth and develop sporophytes. 
When the gametophyte of a polypodiaceous fern is of suf- 
ficient vigor one to several or many normal embryos or sporo- 
phytes may be nourished and brought to independent existence. 
This investigation was done under the direction of Professor 
D. M. Mottier, at Indiana University, and I wish to express my 
thanks to him for his invaluable aid in the work and for the 
helpful criticisms given during its course. 
INDIANA UNIVERSITY, 
BLOOMINGTON, INDIANA 
LITERATURE CITED 
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