570 THE AMERICAN NATURALIST. [Vor. XXXIX. 
sions of Pringsheim and Stahl in species of Funaria, Hypnum, 
and Amblystegium and obtained negative results in a number of 
other forms, and presents an excellent review of the subject. 
Lang (:o1) discovered that small pieces of the sporophyte of 
Anthoceros levis when laid on damp sand produced green out- 
growths which took on the structure of young gametophytes and 
developed rhizoids. These aposporous gametophytes most com- 
monly arose from subepidermal cells, but they may come from 
any layer of the cortex down to the archesporial cylinder. It 
seems probable that the mosses at least among the bryophytes 
are able to reproduce themselves apogamously without difficulty, 
when normal processes of sporogenesis are interfered with and 
if the sporophytic tissue is in contact with moisture. 
The leptosporangiate ferns, however, furnish the most con- 
spicuous illustrations of apospory as they do of apogamy. 
Indeed, the two phenomena are known to occur in the same 
form in a number of instances (e. g., Athyrium filix-femina, 
Nephrodium filix-mas, Scolopendrium vulgare, Trichomanes ala- 
Zum, etc.). Beginning with the discovery by Druery (’86a, 
'86b) of apospory in Athyrium filix-femina and its variety 
clarissima the list has steadily grown until now apospory is 
recorded for about ten forms. In Druery's forms the prothalli 
developed from arrested sporangia and the spore alone is left out 
of the life cycle. But Bower (86) very shortly brought forward 
In Polystichum angulare pulcherrimum a form in which prothalli 
are developed as simple vegetative outgrowths from the tips of 
the leaves and the life history is thus shortened by the omission 
of both spores and sporangia. This condition is exactly analo- 
Sous to the development of protonemata from vegetative cells of 
the sporophytes of mosses and Anthoceros. The following year 
Bower (87) presented a very full account of the forms of Athy- 
rium and Polystichum just described, and a general discussion of 
the phenomenon of apospory. Bower ('88) then extended the 
illustrations of apospory to two species of Trichomanes, of the 
Hy menophyllacez ; Farlow (89) reported it for Preris aquilina, 
and Druery (93) in Lastrea pseudo-mas cristata and (95) for 
UN vulgare crispum. The exceptional amount of : 
lation both in nature and under cultivation has not been 
