332 SCIENCE PROGRESS. 



Apogamy which was discovered by Farlow in Pteris 

 cretica 1 in 1874 and investigated in detail in this and two 

 other species by De Bary - in 1878, is now known in a 

 considerable number of species of Ferns. As in the case of 

 apospory a list of these will be given and the general nature 

 of the phenomena briefly considered. 



Todea africana? Aspidium aat/eatum. 10 



T. rividaris.^ A. angulare 10 



T. pellucida.^ A. frondosum. w 



Osmunda regalis:' Doodya candata. 11 



D. Aspera. 16 



Athyrium Filix-ftxmina}' 1 



Ceratopteris tha/ictroides. b A. Niponicum.™ 



Pteris cretica . 6 Scolope?idrium vu/gare. 10 



(?) Pt. serrulata. 1 Notochlcena dista?is. l?J 



Nephrodium Filix-mas. % 



N. falcatum? Trichomanes aiatum. li 



N. dilatatum.™ 



JV. Oreopteris. 10 (?) Botrychiiim virginianum. Xh 



Apogamy may be defined, in the light of our knowledge 

 of the cases in the above list, as the direct vegetative 

 production from the prothallus of a complete sporophyte, 

 or of any member or group of members of the latter, or of 

 tissues characteristic of the sporophyte within the prothallus. 

 In the first described cases a perfect sporophyte, which 

 continued its growth in the normal manner, was formed on 

 the under surface of a flat prothallus of the ordinary shape. 

 There was more or less complete absence of archegonia 

 from the prothallus in the substance of which tracheides 

 were developed. A comparative review of the known 

 cases shows however that they form a series as regards the 

 directness of the origin of the sporophyte. It is convenient 

 to describe the phenomena in this order, although it must 

 be remembered that a single culture may show several of 

 the forms here distinguished. Changes in the form of the 



1 Farlow ( 1 ). 2 De Bary. 3 Sadebeck. 4 Stange. 



5 Leitgeb. c Farlow (1) ; De Bary. 7 Trow. 



8 De Bary ; Kny. Lang (2). 9 De Bary. 10 Lang. 



11 Stange ; Heim. V1 Druery (5) ; Lang (2). 13 Berggren. 



14 Bower (5). 15 Jeffrey. 16 Mentioned by Sadebeck (2) p. 34. 



