102 



C- Fertile fronds. Fully bipinnate; lower segments bead-like, 

 the upper partially unrolled; secondary rachises si)reading. 



D. Var. obtusila/'ata, Torr. Pinnae pinnatifid throughout their 

 whole extent; segments very strongly re%-olute, those nearest the base 

 of the pinnae sometimes bead-like, as in normal fertile fronds • spo- 

 rangia present m some of the indusia, even when the segments are 

 only moderately revolute. 



E. Sterile fronds. \-\ the normal size; pinnae cut entirely to 

 the midribs m their lower half; primary rachis wingless; margins 

 moderately revolute ; indusia present, conspicuous, 2-6 to each seg- 

 ment ; sporangia none, or merely rudimentary. 



F Sterile fronds. Form similar to " E " but with pinnae less 

 deeply cut and with mere traces of indusia on the basal segments. 



U Sterile fronds. Size and Outline normal; primary rachis only 

 slightly winged ; margins slightly revolute. 



H. Normal sterile fronds with primary rachis broadly winged, 

 except between the lowest pairs of pinnae. 



It will thus be seen that there may occur all possible forms in- 

 termediate between the sterile and fertile fronds, and that Dr. Tor- 

 rey s var. obtusilobata is on the boundary line between the two 



In the present instance the cause of this variation seemed very 



apparent. The meadow in which these forms were found was cut 



a;e m June, before the fertile fronds were grown, thus destroying 



he earher-formed sterile fronds. The vitality of the plant thus find 



ing no outlet save through the growing fertile fronds, and the plant 



be?^^een^rh? T^.T^ ""^ ^''^^"f ' ^ '^'"^^ ^^^^ ^^^^^^^^ intermediate 

 between the fertile and sterile fronds. The following facts may 

 serve to suostantiate this view: b^'tuibuia) 



I Wherever the sterile fronds had been entirely cut away the 

 variations appeared which approximated most closely to the sterile 



2. Where the sterile fronds were only partly destroyed on one 



Z. Where the sterile fronds remained intact, no variations were 

 found, even after diligent search. variations v\ere 



,;i J- ^" P'^^f ^^'l^ere the plants were too much reduced to bear fer- 

 tile fronds under favorable conditions, no variations occurred even 

 when the sterile fronds were entirely cut away. 



Whether the above explanation will prove satisfartnrv for nil 

 forms of the so-called var. Itusilobata whenever found reman an 



anritToilld'h:." VT ^'"^^^' '^°r?^' obtusilobata has no pla e" 

 and It would be well if many more of other numerous forms thaihave 



■s:Tec:";^ '" ^'^ ''^"^>' ^^ '''^''^'' ^°"'d ^^ consigned'to a gra": 



West Goshen, Conn. Lucien M. Underwood. 



96. Fertilization of Rhexia Virninira t t i 



dered.howe^r the. pollen Jclpel^r^'fuc^a^'t r r/XsTof 



Rhexia ^r.^ Cassia, mdehiscent, with small and, in the p es'nrcase 



almost invisible pores. Nuttall seems to have' felt the^ same S 



