ETTER: POLYEMBRYONY IN POLYPODIACEOUS FERNS 97 
a.size of approximately 300-400 cells; while, in his f. 25B, is 
shown what he believes to be a unicellular embryo, with disin- 
tegrating nucleus, collapsing, as it seems to have been aborted 
through embryonic competition. This might have been only 
an old egg-cell disintegrating. The venter indicates no decided 
development as should be expected in the presence of a zygote. 
If this, however, is a unicellular embryo, three or four, and prob- 
ably more, have been observed by me during this study on the 
same gametophyte along with one or two other larger embryos. 
n preparing demonstrations for class use observers have 
noted the occurrence of two or three and possibly four em- 
bryos per gametophyte, but embryos that had reached the 
stage with the first leaf evident were not reported. When 
small embryos were observed along with a much larger embryo 
on the same prothallium, it was noted that the smaller ones were 
evidently suffering from the competitive struggle, as was ap- 
parent by the shrunken appearance of the cells (see Buchholz, 
22}, p.'264). 
Goebel (’87) reported the occurrence of several embryos on 
individual prothallia of Vittaria, some of which bore also a 
larger sporophyte in addition, and stated further that he had 
no doubt that several sporophytes might come from a single 
prothallium. 
Among the Lycopodiales and Equisetales the occurrence of 
two to several embryos per gametophyte has been reported and 
figured in many instances. 
Up to the present time little attention has been devoted to 
the subject of polyembryony in ferns, and especially to the 
development of polyembryony experimentally. 
This investigation was undertaken for the purpose of deter- 
mining whether or not polyembryony existed in Matteuccia 
Struthiopteris (L.) Todaro (Onoclea Struthiopteris Hoftm.). 
It was later extended to include Onoclea sensibilis L., Dryopteris 
mollis (Jacq.) Hieron., and Pteris longifolia L., and the attempt 
was made to determine to what extent plural embryos could 
be developed experimentally. 
_ MATERIALS AND METHODS 
The spores of Matieuccia Struthiopteris, from which the 
prothallia were grown, were obtained through the courtesy of 
