THE AMERICAN BOTANIST 



31 



which in other ferns, at least, is apparently dependent upon a 

 continuous supply of moisture. Until recently, it has been im- 

 possible to say whether the prothallia of rock-loving ferns were 

 able to endure drsang" like the mosses or not since no attention 

 appears to have been g-iven to this phase of fern study, but 

 F. L. Pickett has now made some experiments with the 

 prothallia of the walking fern {Cainptosorus rhizophyUiis) 

 which seem to prove that even this microscopic plant can endure 

 long periods of drouth unharmed. Full grown prothallia were 

 exposed to dry air for from one to two months and came 

 through in good condition. That all fern prothallia are not 

 able to do so was shown by the behavior of some prothallia of 

 the ostrich fern which under similar conditions died after an 

 exposure of two days. The walking fern inhabits the drier 

 ledges of limestone rocks and the ability of its youthful stages 

 to resist drouth has no doubt been an important factor in the 

 occupation of its habitat. 



Value of Novelties. — It is a mistake to suppose that 

 plant forms are fixed or stationary. New and superior varie- 

 ties are constantly appearing, often in the wild but probably 

 more frequently among the specimens of the nurser}niian and 

 gardener since cultivation seems to have a tendency to favor 

 variation. If the discoverer of such forms will take the trouble 

 to preserve and further improve them, he may often find him- 

 self possessed of plants with considerable monetary value. In- 

 stances of plants that have appeared in the wild and subse- 

 quently w^on great favor in our gardens, have been mentioned 

 recently in this magazine. A much longer list, beginning with 

 Burbank's novelties, could be made of those forms that have 

 originated in cultivation, for Burbank is only one of a great 

 number engaged in improving plants. Any seedsman's cata- 

 logue will show many forms originated by others. In many 

 cases these forms have appeared unexpectedly, exactly as the 

 new forms growing wild have done, but often, also, they have 



