TRANSACTIONS OF SECTION K, 799 
compressed remains of mosses with numerous fragments of Alpine willows. ‘The 
following plants have been recognised :—Salix reticulata, L., Empetrum nigrum, 
L., Hypnum fluitans. 
The character of the peat differs from layer 1, as a fine sandy silt occurs here 
mixed with the moss remains. 
A third peat layer runs through the clay about a foot above the second layer, 
made up of mosses, Salix herbacea, S. reticulata, and a few Empetrum stems, 
The upper surface of the clay is reached a few inches above the third peat bed. 
A well-marked layer of Arctic plants rests upon the surface of the clay, the 
following species having been recognised :—Salex reticulata, L., S. herbacea, L., 
S. Lapponum, L., S. Myrsinites, L., 8S. Arbuscula, L. Numerous Eimpetium 
stems are mixed with the willow remains. 
The whole section above this layer consists of compact peat, and no further 
clay occurs. The peat, however, is not of the same character throughout. Above 
the Arctic plant bed the peat is chiefly composed of Sphagnum remains, and this 
passes upwards into a well-defined layer of shrubby willows, the stems being about 
1-3 inches in diameter. Above this Sphagnum peat is again encountered for 
about 2 feet, yielding to a second layer of willow. ‘This is overlaid by Sphagnum 
peat mixed with Carex sp. and Zriophorum remains. About 2 feet below the 
present surface of the peat abundant remains of the rhizomes of Sedum Rhodiola 
occur. The presence of this plant in such quantities near the surface of the recent 
peat is of interest, as it is only found very sparingly at the present day on the 
Pennines at Highcup Gill and Cronkley Scar. The present surface of the peat 
shows signs of rapid and extensive denudation. Sphagnum is almost absent from 
the district, and no peat appears to be forming at the present time. 
5, Plants of the Northern Temperate Zone in their Transition to the High 
Mountains of Tropical Africa. By Professor A. ENGLER. 
_ In building up theories of the evolution of species, those types which are either 
fully identical or appear as closely allied forms in widely separated localities have 
always received special attention. There is a large number of cases of single 
or nearly allied species which are disjointedly distributed in a north-and-south 
direction across the Equator. Sir Joseph Hooker was the first to give a list of the 
so-called European types on Cameroon Peak. Now we know that many species 
of the same character have been found on the Kilimanjaro and other high 
mountains of tropical East Africa. In considering these plants the following 
questions must always be borne in mind :— 
1, Are they identical with the forms living in other latitudes, or do they show 
any small variation from them ? 
2. Is there any possibility of their having originated from a species which was 
once distributed throughout the intermediate area between the present localities, 
or in the lower regions, which has developed itself into identical or convergent 
highland forms in the higher regions? Or is it to be supposed that the seeds have 
been brought by birds or wind across so many latitudes ? 
3. What are the means of transportation of seeds and fruits ? 
4, What is the power of germination? Especially, how long are the seeds able 
to keep it ? 
5. Ser do the plants cultivated in Europe from tropical seeds compare with 
their closest relatives which are indigenous to Europe? 
Experiments to answer questions 4 and 5 have not yet been instituted. But 
whatever the results may be, they will not unsettle the assumption of the close 
affinity of an African to a European plant when based upon morphological 
comparison. 
Regarding question 2, the answer is given for those plants which are isolated 
in the high mountains of Africa, whereas there are many closely allied forms in 
Europe, This answer is definitively settled in the case of those species whose 
