Vegetative Production of Flattened Protonema. 49 
stem, this order was not invariable; in fact the succession was 
frequently acropetal, and in other cases there was no definite 
succession at all. 
III.—Conclusion. 
Apart from Sphagnum and Tetraphis , none of the mosses which 
have flattened protonema appear to have been recorded as producing 
protonema vegetatively, but since the production of protonema from 
various parts of the leafy gametophyte is so common among mosses 
it appears likely that these forms with flattened protonema arising 
from the spore will be found on further investigation to be capable 
under natural or induced conditions of producing vegetative proto¬ 
nema, and it will be interesting to know whether the protonema 
thus produced is flattened like that arising from the germinating 
spore. In this connexion it is interesting to note that among the 
Hepaticae the formation of the new plant from a germinating gemma 
takes place in the same way as in the germinating spore of the 
same species; in most cases the germinating gemma or spore gives 
rise to a germ-tube at the end of which the young shoot is developed, 
but in those forms which have discoid gemmae ( Aneura , Radula, the 
Lejeuneaceae) the spore gives rise to a similar discoid protonema 
from the margin of which the shoot arises exactly as in the case of 
the gemma. 1 
The observations here recorded would appear to support the 
view that in Tetraphis, as in Hepaticae with discoid gemmae and 
discoid protonema, the gemmae may be regarded as homologous 
with protonema though different writers have interpreted the 
gemmae of Tetraphis as modifications of antheridia, paraphyses, 
mucilage-hairs, etc. This is also apparently the first case on record 
of flattened protonema arising vegetatively from the gametophyte 
of a moss under natural conditions as distinguished from cultures. 
I wish to express my thanks to Mr. W. B. Grove for his kind 
interest and advice in connexion with this paper, and to Dr. Cavers 
who helped by supplying references to the literature and suggesting 
the comparisons between Tetraphis and the other Bryophytes 
mentioned in the introductory and concluding portions. 
> See Cavers, “Asexual Reproduction and Regeneration in Hepaticae.” 
New Phvtolooist, Vol. 4, 1903. 
