Apogamy in Ferns . 191 
and probably the Ascomycetes, and also the growing number of instances 
of apogamy in prothallia induced by cultural conditions, as well as such 
cases of obligate apogamy as that of the polydactyla varieties of the Male 
Fern. 
As a sub-class of the eu-apogamous developments it might be 
convenient to distinguish as parthenapogamous those forms in which the 
sporophyte originates from a (premeiotic) oosphere. In this way it will 
be possible to avoid confusion with parthenogenesis. It is true that at 
present we do not know any well-founded cases of parthenogenesis, but 
such may nevertheless be discovered. It would of course involve the origin 
of the sporophyte directly from the postmeiotic unfertilized oosphere, 
which would then rise to give a sporophyte with a similar nuclear character. 
The known examples of parthenogenetic Echinoderm larvae artificially 
produced indicate the desirability of keeping an open mind as regards the 
possible occurrence of parthenogenesis, and it may be pointed out that 
if Lastrea pseudo-mas var. cristata apospora , when it first developed from 
a spore, had possessed archegonia it might have been quite possible for 
a parthenogenetic production of the first sporophyte to have taken 
place. 
When apospory, and with it the omission of meiosis, has occurred 
in the life-cycle, then an apogamous development seems the only way of 
continuing the life-history ; and, vice versa, it is evident that apospory might 
also be correlated with parthenogenesis. 
We propose to present in the following table a suggestion for the 
classification of the various apogamous and aposporous types, but in 
framing such a classification we have sought to avoid making it too 
cumbrous by too minute subdivision. We are well aware, however, 
that no single form of classification is likely to meet with universal 
acceptance, and we only offer this as one which we have found useful 
ourselves. 
A. After Meiosis. 
1. Normal fertilization : 
Example : the ordinary life-history of archegoniate plants. 
1. Pseudapogamy (facultative or obligate) : 
Examples: Lastrea pseudo-mas vars. polydactyla ; Uredineae (Black- 
man). 
3. Euapogamy. 
Example : Lastrea pseudo-inas var. cristata apospora at its first 
origin. 
4. Parthenogenesis : 
No case at present definitely known. 
