85 



The Influence of Certain Environic Factors on the Devel- 

 opment OF Fern Froth alll\. 



David M. Mottiek. 



[Alistract.l 



SiKPics (if till' t'dlliiwiii.i: fi'i'us were used in the exiieiiiueuts : OiiocIe:i 

 sti'utliiupteris (I>.| lldffiii. Dryoi)teris stipularls (Willdl Maxoii and 

 "Xophrodiuin iiKille." 



ri-dtliallia (if (_). struthitiiitt-ris which had devehiued iiniiier<ius aiithe- 

 ridia, Init which were much too small to bear arcliegonia. were trans- 

 planted to separate dishes and allowed to grow under favorable condi- 

 tiiiiis. S.inie of these developed into large prothallia and bore archegonia. 

 The fact (hat female jirothallla of this fern, if kept growing for some time 

 without the fertilization of any of the egg-cells, may develop antheridia. 

 has already been recorded in an earlier publication (Mottier, Bot. Gaz., 

 .10; 2on-2i;;, T.tlO). 



S] lures I if all of the above named species were found to germinate 

 podily. nr not at all, if the cultures were kept in direct sunlight in the 

 greenhouse from the time of sowing. In cultures in whicli prothallia devel- 

 oped, nearly all plants were small and bore only antherladia, a very few 

 only becoming large enough to produce archegonia. 



Three cultures. A. B, and C, of Onocles struthiopteris were sown A]iril 

 1», litll. Tliey were placed in a position to receive direct sunlight, but 

 during the brighter hours of the day cheese cloth was placed over the bell 

 jars under which the cultures were kept, to diminish Sdmewhat the inten- 

 sity of illunnnation. On April 30 all three cultures seemed to have made a 

 favorable beginning, the majority of tlie prothallia being heart-shaped l)ut 

 not large enougli to bear archegonia. A and B were now placed in a 

 position in the greenhouse to receive good diffused light, but no direct 

 sunlight save for only a short time in tlie early morning. Culture C was 

 left in the original position of direct sunlight except the protection given 

 iiy the cheese cloth from about 9 :oO a. m. to 3 :<X) p. m. during days of 

 l)right sun. A and B developed into fine cultures, while in C nearly ali 

 plants remained small, bearing antheridia only. 



All cultures were grown in earthern saucers upon earth which had 

 been previously sterilized in a steam sterilizer. They were watered by 

 means of sub-irrigation. 



