84C coSxMos. 



more so, as Ehrenberg, as I have already remarked, has dis- 

 covered that the nebulous dust or sand which mariners often 

 encounter in the vicinity of the Cape Verd Islands, and even 

 at a distance of 380 geographical miles from the African shcrc, 

 contains the remains of eighteen species cf silicious-shelled pol- 

 ygastric animalcules. 



Vital organisms, whose relations in space are compns^d un 

 iler the head of the geography of plants and animals, may be 

 ijonsidcred either according to the difTerence and relative num- 

 bers of the types (their arrangement into genera and species), 

 or according to the number of individuals of each species on a 

 given area. In the mode of life of plants as in that of ani- 

 mals, an important difference is noticed ; they either exist in 

 an isolated state, or live in a social condition. Those species 

 of plants which I have termed social* uniformly cover vast 

 extents of land. Among these we may reckon many of the 

 marine Algaj — Cladoniae and mosses, which extend over the 

 desert steppes of Northern Asia — grasses, and cacti growing 



spontanea ant primaria'). " If," says he, " animals have not been 

 brought to remote islands by angels, or perhaps by inhabitants of con 

 tiuents addicted to the chase, they must have been spontaneously pro- 

 duced upon the earth ; although here the question certainly arises, to 

 what purpose, then, were animals of all kinds assembled in the ark?" 

 "Si e terra exortaj sunt (bestiae) secundum originem primani, quando 

 dixit Deus: Producat terra animam vivam ! multo clarius apparet, non 

 tam reparandorum animalium causa, quam figurandarum variarum gen- 

 tium (?) propter ecclesiae sacramentum in area fuisse omnia genera, si in 

 insulis quo trausire non possent, multa animalia terra produxit." Augus- 

 tinus, De Civitate Dei, lib. xvi., cap. 7 ; Opera, ed. Monach. Ordinig S. 

 Benedicti, t. vii., Venet., 1732, p. 422. Two centuries before the time of 

 the Bishop of Hippo, we find, by extracts from Trogus Pompeius, that 

 the generatio primaria w^as brought forward in connection with the 

 earliest drying up of the ancient world, and of the high table-land oi 

 Asia, precisely in the same manner as the terraces of Paradise, in the 

 theory of the great Linna-us, and in the visionary hypotheses- entertain- 

 ed in the eighteenth century regarding the fabled Atlantis: "Quod si 

 oranes quondam terras submersie profundo fuerunt, profecto editissi- 

 mam quamque partem decurrentibus aquis primum detectam ; humil- 

 limo autem solo eaudem aquam diutissime immoratam, et quanto prior 

 quajque pars terrarum siccata sit, tanto prius animalia generai'e ccepisse. 

 Porro Scythiam adeo editiorem omnibus terris esse ut cuncta flumiua 

 ibi nata in Mteotium, turn deinde in Ponticum et iEgyptiura mare de- 

 currant." — Justinus, lib. ii., cap. 1. The erroneous supposition that the 

 land of Scythia is an elevated table-land, is so ancient that we meet 

 with it most clearly expressed in Hippocrates, De ^re et Aquis, cap. 

 6, $ 9G, Coray, "Scythia," says he, "consists of A.gh and naked 

 plains, which, without being crowned with mountains, ascend higher 

 and higher toward the north." 



* Humboldt, Aphorismi ex PhysioUgia Ckemicr P!^^^arum in the 

 Flora Fribergensis Suhterranea, 1793, p. 178. 



