lO 



NATURE 



[November 5, 189: 



small black aromatic tasting seeds like those of the culti- 

 vated cardamom. If ever planters go into Africa, the 

 cardamom will be an important product of the soil for 

 commerce, for there are vast tracts of forest with the 

 climate, soil, and checkered shade which are necessary 

 for the cultivation of the cardamon. Orchilla weed 

 should also become a valuable article of commerce ; it 

 grows in many parts of the forest. I consider, however, 

 that when the great forest of Central Africa is opened 

 I'p to civilization, by far the most valuable article of 

 commerce will be india'-rubber, the want of which is 

 increasingly felt in the civilized world. Now that electri- 

 city is so much used for various purposes, the demand 

 for india-rubber grows larger and larger : the supply 

 which is shut up in the African forest is practically un- 

 limited. There are various trees of the fig tribe which 

 yield this product, but by far the greatest amount is 

 contained in the india-rubber vines ^ which abound in 

 the forest and hang from almost every tree. In cutting 

 our way through the forest in some places, we got covered 

 with the milky glutinous sap, which dropped upon us 

 from the vines we cut through. 



"The natives know its value, and use it largely for 

 smearing the inside of their buckets in order to make 

 them hold water. They use it largely also for covering 

 the ends of their drum-sticks. The india-rubber obtained 

 is of a clear, yellowish colour, like glue, and is of the 

 most elastic description. 



"In the forest region I saw no water-lilies, but in 

 Emin Pasha's Province, in the Bari country, I saw two 

 kinds.2 They were both about the size of an ordinary 

 white water-lily, and the leaves and flowers floated on the 

 surface of the water, but the stalks and formation of the 

 leaves and flowers was finer and more slender. One was 

 of a pink coral-like colour, not white like the Zanzibar 

 lily, and the other of a pale bluish lavender. They were 

 growing in small clear pools only a few miles apart in the 

 valley of the Nile, at an altitude of about 3000 feet above 

 the sea. 



" One of the most interesting botanical discoveries I 

 made in the forest was the discovery of a wild orange- 

 tree. During our march through the forest I had con- 

 tinually come upon trees varying from 8 to 15 feet high. 

 They had double leaves of a peculiar shape, which had a 

 delicious smell like orange leaves ; the branches were 

 covered with long sharp thorns, and I at once pronounced 

 them to be orange-trees. My fellow officers smiled 

 incredulously, and exclaimed: 'Orange-trees^ in the 

 middle of the forest ! ' But I held to my opinion, and 

 just before reaching the open country, I came upon a tree 

 with both flowers and fruit upon it. The flowers were 

 exactly the same as the flowers of a cultivated orange- 

 tree. The fruit, which was green, was about the size of a 

 marble. On cutting through it with a knife I found it 

 had the same divisions as an ordinary orange, but each 

 division was full of small seeds, which were very bitter 

 and aromatic. On reaching Emin's Province I told him 

 about it, and he regretted very much that I had not 

 brought a specimen with me, for he was a good botanist, 

 and wished to add it to his collection of dried plants. He 

 told me my discovery was doubly interesting, as many 

 years before a German had penetrated the forest on the 

 west coast of Africa, and reported that he had found wild 

 orange-trees. His story was discredited, and now our 

 discovering the orange-tree in the forest pointed that his 

 report was after all true. 



" 1 have not space to speak much about the flowers we 

 saw in the open country, but will say a few words about 

 those flowers which we found at a high altitude on the 

 slopes of Ruwenzori, or the Mountains of the Moon. 



' Landolphia. 



^ Nymphaa stellata and N. Lotus are both plentiful in Upper Nile-land. 



3 This reads like a tree Citnis, and if -- ■- — --' '- 



Lieutenant Stairs who made the ascent of the mountains, 

 gives the following facts in his report : — 



"'The barometer stood at 2 no, thermometer 70*^ F. 

 Ahead of us and rising in one even slope stood a peak, 

 in altitude 1200 feet higher than we were. This we now 

 started to climb, and after going up a short distance 

 came upon three heaths. Some of these must have been 

 20 feet high, and as we had to cut our way foot by foot 

 through them our progress was necessarily slow. Here 

 and there were patches of inferior bamboos, almost every 

 stem having holes in it made by some boring insect, and 

 quite destroying its usefulness. Under foot was a thick 

 spongy carpet of wet moss, and the heaths on all sides of 

 us we noticed were covered with " Old Man's Beard" 

 {Usnea). We found great numbers of blue violets which 

 had no smell, and from this spot I brought away some 

 specimens of plants for Emin Pasha to classify. The 

 altitude was 8500 feet. We found blueberries and black- 

 berries 1 at an altitude of 10,000 feet. The following 2 are 

 the generic names of the plants collected as named by 

 Emin Pasha : — 



Clematis. 



Viola. 



Hibi>cus. 



Impatiens. 



Tephrosia. 



Glycine. 



Rubus. 



Vacciniuir. 



Begonia. 



Peucedanum. 



Gnaphalium. 



Helichrysum. 



Senecio. 



Sonchus. 



Erica arborea. 



Landolphia. 



Heliotropium. 



Lantana. 



Moschosma. 



Lissochilus. 



Luzula. 



Carex. 



Anthistiria. 



Adiantum. 



Pellaa. 



Fteris aquilina. 



Asplenium. 



Aspidium. 



Polypodium. 



Lycopodium. 



Selaginella. 



Marchantia. 



Parmelia. 



Draca;na. 



Usnea. 



Tree Fern.' 



" These were just a {&^ specimens Lieutenant Stairs 

 brought down with him. But the slopes of Ruwenzori 

 will, when properly explored, yield numbers of unknown 

 treasures to be added to the Botanical Encyclopaedia. 



" For many weeks we drank coffee which we made 

 from the berries of the wild coffee-trees which abound 

 on the highlands round the great lakes of Central Africa. 

 The Arabian coffee was originally supposed to have come 

 from Kaffa, in Abyssinia. That which we found in Karagwe, 

 Ankori, and Uganda is equal in flavour to the finest Ara- 

 bian coffee, and will, when Central Africa is opened up, 

 be another of the chief articles of commerce. 



" I. A. M. JEPHSON." 



no species is hitherto known there. 



NO. I 149, VOL. 45] 



IS an interesting discovery, as 



TO IVN FOGS AND THEIR EFFECTS.^ 



T T NTIL 1880 the formation of fog was looked upon as 

 ^ arising simply from the separation of liquid water, 

 probably in the form of hollow vesicles, from an atmo- 

 sphere saturated with aqueous vapour ; but in that year 

 Aitken showed that really the determining cause of the 

 separating out of liquid water, and consequent formation 

 of fog, was dust present in the air. He pointed out that 

 a change of state, a gas passing to a liquid, or a liquid to 

 a solid, really always occurred at what he terms a " free 



' It would be very interesting to have these identified. The two highest- 

 known species of Rubns are pinnatus and rigicius, at 5000-6000 feet. 



^ This hst is in Stanley's bouk. The Viola is no duubt abyssinica, com- 

 mon to the mountains of Madagascar, Abyssinia, the Camerooiis, and Fer- 

 nando Po. There are three heaths known on ihe high mountains of Central 

 Africa, viz. Erica arborea, Ericinella Mannii, and Blaeria spicata. 

 There is no Vaccinimii known before in Tropical Africa; though three or four 

 are plentiful in Madagascar, and there is one on the Drakensberg, so that its 

 occurrence is most probable. The ferns of Tropical Africa are nearly all 

 species widely spread in other continents. 



3 The paper by Dr. W. J. Russell, F.R.S., introducing the discussion on 

 Town Fogs at the Hygienic Congress. 



