i9i 



as to the origin of alternation of generations were seriously 

 affected. Before these investigations and discoveries, it 

 was assumed that the life cycle was necessarily spore, 

 prothallus, fertilized egg, and finally the sporophyte or 

 fern proper. Apogamy, however, discovered by Professor 

 Farlow, eliminated the sexual act, a vascular structure 

 originating in the prothallus which resulted in an asexual 

 bud, whence at once arose the sporophyte, the life cycle 

 then being spore, prothallus, sporophyte. This, though 

 first remarked in a normal Pteris cvetica, was subsequently 

 found by DeBarry to occur with seeming constancy in 

 an abnormal tasselled form of Lastrea (L. pseudo-mas 

 cvistata) and several other species normal and abnormal. 

 The next discovery was that of soral apospory by the 

 writer, on a form of Athyvium jilix-fcemina, which shortened 

 the life cycle in another way altogether, by eliminating 

 the spore, masses of prothalli being produced, as Professor 

 F. O. Bower subsequently ascertained, from the stalks of 

 aborted sporangia, on the ordinary soral sites.'" Here the 

 life cycle runs thus, sporophyte, sorus, prothallus, fertilized 

 eg£, sporophyte. No sooner was this phenomenon 

 announced than Mr. G. B. Wollaston reported the still 

 more remarkable case of apical apospory in the form of 

 Polystickum angulave (P. ang. pulcherrimum), in which the 

 abnormally long sickle-shaped pinnules had their terminal 

 and segmental apices dilated into prothalli, which when 

 layered ran the normal course, with the exception that 

 resulting plants were invariably defective and depauperate. 

 Here the sorus is eliminated, and the prothalli are produced 

 altogether independently of the usual reproductive sites, 

 by a modification of the tissue of the sporophyte. Several 

 quite independent finds of the pulchevvimum type existed, 



-Druery, C. T. : Jour. Linn. Soc. 21: 354. 1884: 22: 427-440. 

 SS5. Bower, F. O. : Trans. Linn. Soc. 2 : 301-326. 1887. 



