50 NATURAL HISTORY OF PLANTS. 



Pithecolobmm are very rare in Africa and Asia, though, on the contrary, 

 widely spread in America. Mimosa, too, is chiefly American. As 

 for Acacia, it is commoner in tropical and Southern Africa than many 

 other parts of the Old World. The Floras of the Cape, Senegal, and 

 Abyssinia include upwards of fifty species, but it chiefly affects a 

 favoured zone in Australia and the neighbouring parts of Oceania, so 

 that at the present day nearly three hundred species, that is, a 

 little less than three-quarters of the entire genus, are known to 

 occur spontaneously in New Holland. 



The Mimosea possess numerous properties, 1 of which the most 

 remarkable are the astringency of the bark and pericarp, and the 

 presence of a gummy substance in the former, analogous to that of 

 the Pruneae. Grum arabic and all other gums resembling it in solu- 

 bility in water, and chemical reactions generally, are furnished by the 

 Mimosea, and also especially the genus Acacia"- It is well known that 

 most of the gums called Arabic and Senegal gums are produced by 

 A. arabica 3 a species spread over India, Egypt, Arabia, Senegal, and 

 even as far south as the Cape. It has four chief forms or varieties, 4 

 called nilotica, 5 tomentosa* indica, 1 and Kraussiana.* It is the first of 

 these varieties which, at least in great part, constitutes the A. vera 9 

 of authors, a plant long supposed to be the only source of gum 

 arabic. Senegal gum is exuded chiefly from the variety tomentosa, 

 and the Indian gum from indica. However, in places whence such 

 gums are obtained there are other Acacias of different species which 

 supply it. Such are A. adstringens™ giving gum gonatc or gonatie, A. 



1 Endl., Enctiirid., 683. — Lindl., Veg. 6 Benth., loc cit. — II. Bn., loc.cit., 94 A. 

 Kingd., 552; Fl. Medic, 268. — Gttib., Drog. — Acacia arabica W., Spec, iv. 1085. — DC, 

 Simpl., ed. 4, iii. 300. — Rosenth., Syn. Plant. Prodr., n. 134. — Neb-neb of Senegal. — Gommier 

 Diaphor., 1051, 1065. rouge Neb-neb Adans. 



2 H. Bn., in Diet. Fncycl. des Sc. Medic, i. ' Benth., loc. cit. — Mimosa arabica Roxb., 

 254 ; Revision des Acacia Medicinaux, in Adan- PI. Coromand., ii. 26, 1. 149. — Acacia vera altera 

 sonia, iv. 85. Pluk., Almag., 3 (Babool, Babula in Bengalli, 



3 W., Spec, iv. 1085. — DC, Prodr., ii. 461, Burbura in Sanscrit, Nella Tooma in Cingalese). 

 n. 135.— H. Bn., loc. cit., 91, n. 8. 8 Benth., loc cif.—K. Bn., loc. cit.. 96 I'. 



4 Benth., in Hook. Journ., i. 500. 9 W., Spec, iv. 1085.— DC, Prodr., n. 134.— 



5 A. nilotica Dee., Fl. Mgypt., 79. — A. Valm. de Bom., Diet., i. 81. 



eegyptiaca Fabe. — Mimosa arabica Poib., 10 H. Bn., loc. cit., 88. — A. Adansonii 



Diet., Suppl., i. 19. — Spina eegyptiaca Plttk., Gtjiilem. & Perb., Fl. Seneg. Tent., i. 249. — 



Almag., 3. — Spina Acacia; Lobel. — Sant, Sunt Mimosa adstringens Schtm. & TnoNN., Beskr., 



of the Egyptians (see GuiB., op. cit., iii. 363. — 2. — Gommier rouge Gonake or Gonalie 



H. Bn., loc. cit., 95 B.). Adans. 



