APOGAMY, APOSPORY, AND PARTHENOGENESIS 315 



the presence of a cell and nuclear fusion it is classified under 

 le.] 

 (6) The gametophyte is diploid (see under Apospory): 



(a) The sporophyte is developed from the diploid oosphere: 

 observed in some Pteridophyta, viz. certain ferns (Farmer 

 1907), Athyrium Filix-fcemina, var. clarissima, Scolopend- 

 rium vulgare, var. crispum-Drummondce, and Marsilia 

 (Strasburger 1907); also in some Phanerogams, viz., 

 Composite (Taraxacum, Murbeck 1904; Antennaria alpina, 

 Juel 1898, 1900; sp. of Hieracium, Rosenberg 1906): 

 Rosacese (Eu-Alchemilla sp., Murbeck 1901, 1904, Stras- 

 burger 1905 [Fig. 125, C]): Ranunculacese (Thalictrum 

 purpurascens, Overton 1902). [Also in the lily, Atamosco 

 (Pace 1913), and Burmannia (Ernst 1909). Besides this 

 form of apogamy ("ooapogamy" or "generative apo- 

 gamy") Antennaria may also develop embryos from 

 diploid synergids ("vegetative apogamy") and from cells 

 of the nucellus ("sporophytic buddirg"). A similar 

 variety of embryo origins is found in certain other angio- 

 sperms. In many cases the chromosome number in 

 apogamous species is about twice as large as that of nearly 

 related forms reproducing sexually (Rosenberg 1909).] 

 (/3) The sporophyte is developed vegetatively from the gameto- 

 phyte: observed (Farmer [and Digby] 1907) in the fern 

 Athyrium Filix-foemina, var. clarissima. 



In all cases enumerated under Eu-apogamy, apogamy is 



associated with some form of apospory except Nephrodium 



molle, full details of which have not yet been published. 



[It is possible that a behavior like that in Aspidium 



falcatum (le) or in Nephrodium hirtipes (2a/3) may occur 



in Nephrodium molle.] Many other ferns are known to be 



apogamous, but they are not included here because the 



details of their nuclear structure have not been investigated. 



Apospory. The known modes of apospory may be arranged as 



follows : 



1. Pseudapospory: a spore is formed but without meiosis, so that it is diploid 

 observed only in heterosporous plants, viz. certain species 

 of Marsilia (e.g. Marsilia Drummondii) where the megaspore has a 

 diploid nucleus (32 chromosomes) and the resulting prothallium and 

 female organs are also diploid (Strasburger 1907); and in various 

 Phanerogams, some Compositse (Taraxacum and Antennaria alpina, 

 Juel 1898, 1900, 1904), some Rosacese (Eu-Alchemilla, Strasburger 

 1905), and occasionally in Thalictrum purpurascens (Overton 1902), 

 where the megaspore ([and] embryo-sac) is diploid; in some species 



