276 STEIL: POLYPODIUM IRIOIDES 
SUMMARY 
{In an old culture of prothallia of Polypodium irioides, the 
sterile cells of a large number of antheridia and archegonia be- 
came vegetative like ordinary prothallial cells. 
The lid and the ring cells of the antheridia produced prothallial 
filaments and secondary antheridia. 
The archegonia produced similarly from the neck and the 
venter cells filaments and antheridia, but in no case secondary 
archegonia. 
At some time during their course of development, antheridia 
were transformed into prothallia. No such transformations were 
observed to occur among the archegonia. 
The prothallia produced from the sex-organs resembled those 
formed from the germination of a spore. 
Secondary antheridia arising from antheridia and archegonia 
developed actively motile antherozoids. 
Unusual cultural conditions probably diverted the sex-organs 
of Polypodium irioides from their normal course of development. 
No similar case of regeneration has been previously reported 
in a pteridophyte. 
UNIVERSITY OF WISCONSIN, 
MADISON, WISCONSIN 
Explanation of plate 4 
Fic. 1. Antheridia of Polypodium irioides Poir. ; the lower one with a vegetative 
ring cell, the ee one with a prothallial filament of two cells produced by a ring 
cell.” X 2 
IG, 2. a antheridium from the lid cell of which has been produced a filament 
of four cells. The upper ring cell with a secondary antheridium from which the 
antherozoids have escaped. 
Fic. 3. The lid cell (a) of an » antheridium ose vei oy. oe (b and ¢) 
from the lid cell of the latter of wt X 230 
G. 4. Two secondary antheridia produced from a single ring ie of an anther- 
aa ™M 230 
IG. 5. A theridi lik 4 +f roe n 
Fic he upper ring cell has divided and from one oh the cells another an- 
therict iene ssl been posi ge 
t if leh diaint eee 6 is toril lle 
Fig. 7. 
contain numerous chloroplasts. X 200. 
IG An antheridium similar to the above. 93 4. 
Fic. 9. A normal (a) and an abnormal (b) eek mia The upper portion 
of the latter is disintegrating. x 303% 
PG 10. A stage in the transformation of an antheridium into a prothallium. 
200. 
