30 HUMPHREY 



of the leaves as occurs in the majority of ferns. Not infre- 

 quently one finds in the field quite fully developed prothallia of 

 this species early in the autumn before the winter rains have 

 actually set in. It is hardly possible for these to have devel- 

 oped from spores that had germinated at any other time than in 

 spring or early summer. In fact, it has been experimentally 

 shown by Professor Peirce ^ that the prothallia of this species 

 may endure prolonged desiccation without evidence of the 

 slightest injury, for on being moistened they very promptly re- 

 vive and young sporophytes develop normally from these gameto- 

 phytes of the preceding season. Perennial prothallia develop- 

 ing tubers have been reported by Goebel ^ for the allied fern 

 Anog}-amme cheer ofhylla^ common in southern Europe. Such 

 structures belong to some of our liverworts but have not yet 

 been shown to occur in the prothallia of any of our ferns. Aside 

 from the common fern Gymnogranwie, other pteridophytes native 

 to California, e. g., Selaginella bigloveii and S. lefidofhylla^ 

 the latter the well known " resurrection plant," are reported by 

 Campbell in the paper above referred to as remaining in a dry 

 and dormant condition throughout the greater portion of the 

 year, resuming active growth during the rainy season, at first 

 absorbing considerable water through their leaves as do the 

 leaves of Gymnogratiime. 



To test the vitality of those liverworts that had been naturally 

 and then artificially desiccated, a certain number of plants from 

 each lot were placed on moist earth and others in Knop's 

 nutrient solution. In both cases the plants revived promptly 

 and are now growing vigorously, producing fruiting organs in 

 great number. A surprisingly small portion of the thallus of 

 Targionta, Riccta, Fimbriaria and Porella was actually dead ; 

 though in Fossomhronia^ Cryflomitrium and Anihoccros fhy- 

 matodcs only the apical end including a small portion of the 

 thallus appeared to be alive. Within five hours revived plants 

 from each species were fixed with chromic one per cent, fixing 

 solution and run up through the alcohols and bergamot oil to 



2 Campbell, 1904: Resistance of Drought by Liverworts. Torreya, Vol. 4, 

 No. 6, p. 85. 



3 Goebel, 1898 : Organography of Plants. Part II, Vol. i, p. 426. 



