524 Engler . — Plants of the Northern Temperate Zone in their 
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, and having developed themselves 
into identical or convergent highland-forms in the higher regions ? Or is it 
only to be supposed that the seeds have been brought by birds or wind 
across so many degrees of latitude ? 
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. How do the plants cultivated in Europe from tropical seeds compare 
with their closest relatives which are indigenous to Europe? 
No experiments in answer to questions 4 and 5 have yet been 
instituted. But whatever the results may be, they will not be able to 
unsettle the assumption of the close affinity of an African plant to a 
European one when based upon morphological comparison. 
If of two nearly allied forms, Ae in Europe and Aa in Africa, the 
seeds of Aa when cultivated in Europe give the form Ae, it is proved that 
the evolution of Ae is only due to climatic conditions. But if the seeds of 
Aa again give Aa, the assertion of Aa having once originated from Ae is 
not by any means refuted : for the transformation of Aa into Ae may well 
have become fixed during a long period. However, it is much to be 
recommended that many such experiments of cultivation should be made. 
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 definitely settled in the case of those 
species whose European forms belong to a larger group of related plants 
developed in Europe or in the northern temperate zone generally. 
From these, I shall select for discussion principally such forms as, not 
being represented in Egypt, are to be found only in Abyssinia or further 
south. 
Since the first travels of Schimper in Abyssinia, we are acquainted with 
a species of Luzula, growing at 3,600 m. above sea-level, which was named 
L . spicata , (L.) DC., var. simensis , Hochst. This plant was found, later on, 
on the Kilimanjaro also. On the same mountain, another one was collected 
by Prof. Volkens and described as L. Volkensii by Prof. Buchenau. This 
Lnzula seemed to be worthy of more careful examination, since any forms 
at all closely related to L. spicata , (L.) DC., are absent from tropical Africa 
(as well as from Southern Africa). Luzula spicata itself is an arctic-alpine 
plant, and arctic-alpine plants are not observed elsewhere in tropical 
Africa. 
When visiting the Kilimanjaro in October 1902, I had the first oppor- 
tunity of observing these plants on a meadow below the Mue River, at 
about 1,900-2,000 m., in company of other plants more frequently to be met 
