102 ETTER: POLYEMBRYONY IN POLYPODIACEOUS FERNS 
method stated in the foregoing. In three instances both em- 
bryos were left on one lobe. In each case the embryos came 
to independent existence and grew well. Ten prothallia were 
divided so that there was one embryo on each half. Six of 
the ten cases in this experiment developed and came to inde- 
pendent existence. This demonstrates the fact that a portion 
of a prothallium is capable, when isolated, of supporting a young 
sporophyte. 
—— a Ja 
e ———s H 
— 
Fic. 2. Two sporophytes on a single gametophyte of Pteris longifolia 
(as seen from the ventral view), located on opposite sides of the archegonial 
cushion and well back from the sinus 
IG. 3. Regenerated lobe of a iokhaltiedis of Dryopteris mollis, bearing 
two normal, thrifty, young sporophytes, 6 and c, widely separated on the 
er cushion. a, the old half of the sniginal prothallium. 
G. 4. Three sporophytes ona oe lobe of Moltewccia Struthi- 
oa They came in the order as lette 
Two hundred seven ae 3-5 mm. across the lobes, of 
the various species, which bore no embryos, were then divided 
longitudinally through the apical sinus. Apparently very 
little inconvenience was suffered by these severed parts. They 
recovered readily and less than 2 per cent of the prothallia were 
