262 BOTANICAL GAZETTE [MARCH 
valued. Both of these methods are defective in that they fail to recognize 
the importance of non-luminous rays in plant processes, a fact that has been 
thoroughly established by BRown and EscoOMBE.—BARRINGTON Moore. 
Plant formations of Caithness.—A report by CRAMPTON’ on the ecology 
of some of the northern parts of Scotland relates the development and succession 
of the various plant associations to the physiography of the region to an extent 
quite surpassing previous discussions of the vegetation of the British Isles. 
There is also a dynamic point of view maintained throughout and particularly 
emphasized in the study of the progressive and retrogressive phases of the 
moorland formation. The author not only recognizes the stable and suc- 
cessional formations of the topographic cycles, but also the regional successions 
as exemplified in the remains of tundra, forest, and moorland vegetation found 
in the peat mosses. This full appreciation of the dynamics of plant formations 
marks the study as one of first rank, and indicates a decided advance for 
British ecologists 
The extinct formations recognized are the pine forests, the tundra, and the 
arctic peat mosses, all related to the advancing and receding ice sheets of the 
geological period of glaciation, while the existing formations include the alpine 
and subalpine, the moorland, and, in less prominent development, those of the 
drainage system and coastal belt. From the exposure and altitude of most 
of the area studied, associations of sphagnum and other mosses and of the 
heather are the most abundant types of vegetation. Among the problems 
iscussed, two may be cited as of special interest and as indicating to some 
extent the scope of the work. The one deals with the relationship of the Calluna 
mat of the alpine plateaux to the destructive winds, resulting in the develop- 
ment of a series of ridges and troughs of vegetation; the other is a part of the 
ecological relations of the moorland to the drainage system, and demonstrates 
the present decline of the peat bogs with the advance of river erosion. The 
reaction of sphagnum growth upon drainage and erosion is also carefully con- 
sidered, as well as the competition between Sphagnum and Calluna, the two 
most conspicuous members of the moorland vegetation.—Gero. D. FULLER. 
Fertilization in Taraxacum.—RAuNKLIir’s castration experiments on 
several forms of Taraxacum, as well as MURBECK and JUEL’s cytological inves- 
tigations, have proved that parthenogenetic or apogamous development of the 
embryo prevails in this genus. DAnLsTepr later published the view that in 
two or three species of Taraxacum grown in a Belgium garden pollination 
seemed necessary to’seed formation. ROSENBERG has described the normal 
occurrence of the reduction division in the nucleus of the embryo sac mother 
cell of Taraxacum, and HANDEL-MAzzetTI has announced the appearance of 
15 — C. B., The vegetation of Caithness considered in relation to the 
geology. pp. I Edin bus gh: Published under the auspices of the Committee for 
the survey and es of British vegetation. 1911. 
