APOGAMY, APOSPORY, AND PARTHENOGENESIS 315 



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



(b) The gametophyte is diploid (sec under Apospory): 



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



observed in some Pteridophyta, viz. certain ferns I Farmer 

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

 Hum vulgare, var. crispum-Drummond(B f and Marsilia 

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

 Compositas (Taraxacum, Murbeck 1904 : .1 nti nnaria alpina, 

 Juel 1898, 1900; sp. of Hieracium, Rosenberg L906): 

 Rosacese (Eu-Alchemilla sp., Murbeck L901, 1904 3 Stras- 

 burger 1905 [Fig. 125, C]): RanunculaceaB {Thalictrum 

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

 (Pace 1913), and Burmannia (Ernst 1909). Besides tin- 

 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 eases the chromosome number in 

 apogamous species is about twice as large as that of nearly 

 related forms reproducing sexually (Rosenberg 1909).] 

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

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

 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 (2a0) 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, 80 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 Composite {Taraxacum and AnU nnaria alpina, 

 Juel 1898, 1900, 1904), some Rosacea (Eu-AlckemiUa, Strasburger 

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

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



