gto] HOYT—FERTILIZATION IN FERNS 349 
TABLE OF RESULTS OBTAINED FROM PROTHALLI REPLANTED 
SOIL 
) 4 Number of | Number of | Number of 
prothalli | entrances | sporelings 
D. marginalis..............| D. marginalis 6 ° ° 
D. Thelypteris.............| D. Thelypteris 5 ° fe) 
parenmmmasg D. Thelypteris 23 ) ° 
a Marginals |... ss. s.- D. noveboracensis I 3 ° 
Be WOMPEONMNS ys Pteris multifida 10 ° fe) 
Pteris multifida......... P ] 24 24 5 
(eetoeming,..-.....:,. P. multifida 3 Io ° 
Filix-foemina........... A. Filix-foemina 43 6 6 
A Filix-foemina Seana se 9 s. montanum R fo) ° 
A, Filix-foemina .......... As.. platyneuron 8 TO ° 
As. platyneuron............| As. platyneuron 40 ? 6 
As. platyneuron............| A. Filix-foemina and 
| yneuron 2 6 2* 
As, platyneuron............ Camp. rhizophyllus 
. platyneuron I I ° 
Camp. rhizophyllus........ As. platyneuron 12 ete fe) 
* As. platyneuron, 
of the entrances counted that the egg was bad, but the egg is no more 
likely to be bad in the cases of the entrance of a foreign sperm than 
in the cases of the entrance of its own sperm. It is believed, there- 
fore, that the proportion of entrances in which fusions have been 
obtained may be compared in the two cases. 
In the second table, the number of entrances obtained can only be 
approximated, since on the one hand not every entrance is observed, 
and on the other hand an observed entrance does not necessarily 
mean that the sperms have reached the venter. 
These results for most of the combinations tried are not conclusive, 
but taken all together they constitute a considerable mass of evi- 
dence against the occurrence of hybridization in these ferns. Entrance 
of sperms of its own species into 97 archegonia on 59 prothalli, as 
shown in sections, gave 37 fusions; while the entrance of sperms 
of other species into 129 archegonia on 111 prothalli failed to give a 
single fusion. 
The results obtained from replanting the prothalli on soil confirm 
those obtained from sections; all point against the occurrence of 
hybrids among these ferns. : 
The most noteworthy cases observed in sections are the following: 
Sixty-seven entrances of the sperms of Dryopteris Thelypteris into the 
