-5 6- 



rarely produce spores. Other species fruit late in sum- 

 mer when most likely to be exposed to drouth. The fact 

 thus illustrated is of wide application among the ferns, 

 and may have an influence upon the production of such 

 forms as Onocca sensibilis obtusilobata and Osmundc 

 cinnamomea frondosa. Many have conjectured that the 

 last mentioned form is due to a fire sweeping through the 

 locality, while others claim to have found specimens 

 where there were no signs of a forest fire. Drouth at 

 the proper season, however, might account for both oc- 

 currences. 



Prof Atkinson has held that the obtusilobata forms of 

 0)io clca and Struthioptcris can be produced at will by 

 removing the early sterile fronds, but some of those who 

 have tried to duplicate his results have been unable to 

 do so. It may turn out. after all, that dry weather must 

 be taken into account in producing such forms. Many 

 other habits of ferns point to this theory. Practically 

 all tropical ferns fruit at the beginning of the dry season, 

 and our own ferns, with few exceptions, fruit when their 

 habitat is the driest. Everybody is familiar with the fact 

 that specimens growing in dry ground or in sunlight will 

 be more fruitful than specimens of the same species in 

 shade and moisture. The whole subject is worth a care- 

 ful investigation. 



Ferx Gexera axd Species. — The completion of Chris- 

 tiansen's " Index Filicum " gives us new data upon 

 which to base our calculations of the number of fern 

 species. According to this there are 149 good genera 

 and 5940 species. Of course the majority of these are in 

 the Polypodiaceae which is regarded as containing 114 of 

 the genera and 4527 of the species. The next two largest 

 genera are Hymenophyllaceae and Cyatheacea?, contain- 

 ing 459 and 456 species, respectively. That the indus- 

 trious name-tinkerer has been ever with us is shown by 

 no less than 670 generic names that are synonyms, and 

 15,787 specific names that are no longer in use. It is 



