The Means of Distribution of Hepaticcz 
167 
THE MEANS OF DISTRIBUTION OF HEPATIC^. 
By Henry R. Yeates. 
N the issue of *• The New Phytologist ” for October, 1907 1 
Professor Campbell argues that one of the most important 
means of arriving at the antiquity of any group of organisms is the 
study of the present distribution of the group and the means of 
distribution in recent times. This aspect of the subject has for a 
long time been uppermost in the writer’s mind, and has been 
strengthened by the local distribution of those genera which are 
common in our own country. With such hygrophilous plants as 
Hepaticae, built up entirely of cellular tissue and ill adapted to 
survive prolonged periods of drought, their migration is largely 
limited to those areas which afford means for water carriage. 
Every botanist who has made a practical study of the distribution 
of Hepaticse, in any one area, is well aware that they are the 
occupants of the low-lying valleys, where moisture is abundant; 
and when met with in more elevated districts the geological formation 
is such as to connect the station with some valley not far remote. 
Certain genera, from the greater delicacy of their tissues, not 
only require a superabundance of water, but also a comparatively 
high thermal constant for the maturation of their spores, and are 
unable to persist in regions where there is abundant evidence 
of their having formerly flourished. Reboulia heiiiispherica and 
Dumortiera irrigua have all but disappeared from our English 
representatives, and though at the present day occurring sparsely 
in one or two isolated stations, their organs of fructification are 
rarely met with in the mature state. 
Professor Campbell is quite right in discounting the too 
prevalent assumption that because of the lightness of the spores of 
Hepaticse they are specially fitted for the rapid dispersal by wind. 
The writer’s experiments with the spores of Fegatella conica and 
those of other genera are in perfect harmony with those undertaken 
by Mr. H. B. Humphrey, cited by Professor Campbell 2 and the 
conclusion he has arrived at is that not only do these bodies quickly 
lose their power of germination owing to dessication, but that no 
important number of them ever germinate at all, owing to 
unfavourable conditions surrounding the parent structures. Under 
1 D. H. Campbell. On the Distribution of the Hepaticae and its 
Significance, New Phytologist, Vol. VI., p. 203. 
3 l.c. p. 210. 
