530 Engler. — Plants of the Northern Temperate Zone in their 
forms with very tall (up to i m.) stems, as found by me on the Kilimanjaro 
in the upper forest at 2,600-2,900 m., have the same long-cuneate sinuate- 
dentate leaves as specimens from the island Palma, Canary Islands. Other 
specimens 0*5 m. high, collected by Volkens below the Mawensi at 2,700 m. 
in a clump of woods, may be reckoned undoubtedly to var. umbrosa , 
Boiss., being very like specimens of the sub-alpine region of M. Olympus, 
Bithynia. Other specimens, similar to those of Palma, were found by 
Dr. Ellenbeck in the Upper Galla country, in the territory of the Arussi 
Galla, and on the Gara Mulata near Harar at 2,500 m. Agreeing in the 
general shape pf the leaves with the above, but distinct by its numerous 
smaller teeth, is forma 7 neruensis , Engl., 3-5 dm. alta; foliis cuneiformibus, 
dense breviter dentatis 3-4 cm. longis, 6 mm. latis. 
This form, collected on the Meru at 3,500-3,600 m. by Prof. Uhlig, 
has sometimes pods 4-5 cm. long (as in the majority of the forms of our 
polymorphous type), sometimes only 1-5 to 2 cm. long. Specimens grown 
in moist crevices of the summit of the Meru (4,700 m.) have also pods only 
1-5 to 2 cm. long. At the eastern base of the Kibo summit, at 4,800 m., 
Prof. Uhlig gathered specimens both with long and with short pods, the 
first belonging to a form intermediate between meruensis , and another one 
which I call kiboensis . This last one — forma kiboensis , Engl., 1-3 dm. alta, 
foliis inferioribus anguste cuneatis 2-4 cm. longis, 3-5 mm. latis, subintegris — 
shows the greatest differences from all the other forms. In fact, it would 
easily pass as a distinct species if there were not so many intermediate 
forms of the polymorphous type. It was collected also at a lower altitude 
(3,300 m.) by Prof. Hans Meyer and Prof. Volkens, also above Kibosho at 
3.600 m., being one of the last flowering-plants. 
Arabis albida , then, is a polymorphous type originally descended from 
the same protype which A. alpina sprang from. Its various forms are to 
be found from the upper forest-region to the uppermost limit of flowering- 
plants throughout the Mediterranean mountains, from Persia through the 
Caucasus Mountains to the Crimea and through the mountains of Asia 
Minor via Cyprus and the Greek mountains to Sicily, from there to the 
Atlas Mountains of Algeria and Morocco, to Madeira and the Canary 
Islands. The light narrow-winged seeds, being apparently suitable to be 
transported easily by air currents, have reached far distant summits. The 
seeds have found their way to Abyssinia also (for Arabia, the plant is not 
yet recorded up to the present); from Abyssinia, it was distributed to 
Galla Highland and to Kilimanjaro, where, besides the typical forms, the 
tall sylvatic form of 1 m. in height, and, on the other hand, the narrow- 
leaved forms only 10-15 cm. high, were developed by the influence of 
changed conditions of climate. These new forms are therefore of a special 
interest, because undoubtedly they have been formed only by the influence 
of new conditions of life, without any intervention of allied forms. The 
