564 THE AMERICAN NATURALIST. [VOL. XXXIX. 



illustrations of apogamy. Since Farlow's discovery in 1874 of 

 an asexual sporophytic growth from the prothallus of Ptcris 

 cretica the list of apogamous pteridophytes has steadily increased 

 until now the phenomenon is known in perhaps 25 forms. Far- 

 low's investigation was followed by an extended study of De 

 Bary ('78) on a large number of forms in the Polypodiaceas and 

 resulted in the establishment of similar sporophytic outgrowths 

 in Aspidinm falcatum and Aspidium filix-mas cristatitm. De 

 Bary proposed the term apogamy ('78, p. 479) for the general 

 phenomenon and distinguished two forms, apandry the suppres- 

 sion of the male sexual organs which results in a parthenoge- 

 netic development of the egg, and apogyny for the suppression 

 of the female. Sadebeck in the following year reported apog- 

 amy in Todea one of the Osmundacese (Schenk's Handbnch dei 

 Botanik, vol. i, p. 231, 1879) thus extending the phenomenon 

 to another family. And later apogamy was found in Tricho- 

 manes alatum one of the Hymenophyllaceae (Bower, '88) and 

 in Selaginella rupestris (Lyon, :O4, p. 287). 



The most important recent contribution on apogamy in ferns 

 is by Lang ('98, abstract in Annals of Bot., vol. 12, p. 251). 

 This paper presents an able discussion of the phenomenon in 

 its relation to alternation of generations and adds the very 

 interesting discovery of sporangia borne directly on prothalli that 

 were grown from spores. These sporangia were found in clus- 

 ters on a thickened lobe or process from the prothalli of Scolo- 

 pcndrinm vnlgare ramulosissimnm and Neplirodiwn dilatmn 

 cristatum gracile. The sporangia were perfectly normal in 

 structure and they matured spores. It is probable that the 

 process is itself sporophytic in character, i. e., made up of cells 

 with double the number of chromosomes of the true gametophy- 

 tic portion of the prothallus, but cytological details are not 

 known. Lang's study of the apogamous development of sporo- 

 phytic buds on several forms of the Polypodiacese is the most 

 detailed work on apogamy in the pteridophytes yet published. 

 The apogamous growths appeared as the result of cultures which 

 were watered entirely from below and exposed to direct sun- 

 light, important departures from normal conditions surrounding 

 fern prothalli. In all cases the prothalli developed normal 



