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INTRODUCTION. By Dr. A. Seitz. 
regularly and certainly, so that nature, particularly the animal world, is adapted to them, and further that 
man himself, if he understands as the old Egyptians did, has learnt to cooperate with the waters, to apply 
them to profitable irrigation, and to establish a rational system of drainage. 
The genuine forest region in Africa only spreads over that part of the torrid zone which extends 
from 10 1 N. to about 20'’ S. But even here the actual primitive forest only reaches the coast here and 
there, neither does it extend in an unbroken mass to the high-lying interior, but steppes covered with 
gigantic grasses intersect it with ever increasing frequency, and merge more and more together to form 
the vast grass-covered plains which spread over almost the whole of Central Africa. The forest becomes 
always scantier and more broken up into strips towards the tableland, until at last only isolated mangrove 
trees, comparable to scattered erratic rocks, break the uniformity of the steppe. 
Thorns are a striking characteristic of African vegetation. It is true that in America and India w r e 
meet with spinous growths enough, but still only isolated, scattered about in thickets of harmless vegetation. 
But in Africa there is scarcely a plant or a shrub which does not sting, scratch, hook or catch in a manner 
most annoying to the traveller. Even the high-growing mimosas and acasias produce thorns, which, moreover, 
they cast off, and which then lie about under the trees always joined together in threes, and, since in 
consequence of the prickles projecting in three directions one thorn must always point upwards, act as 
traps for the feet. 
This inaccessibility of the plants which spread over Africa at the present day is a proof of a 
characteristic peculiarity of the vegetation, which again solves many a zoogeographical enigma. The present 
tlora of Africa, indeed, is but a scanty remnant, the remains of a once enormous number of species of 
plants from which almost all the edible leaf-bearing ones have been exterminated — exterminated by the 
quite phenominal richness of Africa in leaf-eating animals; a richness in herds of ruminants, pachydermata 
and perissodactyls, such as no other part of the world has ever known. Having seen at times how, before 
one herd had disappeared on the horizon, the next had already appeared to eat what was left, and how 
every prickly plant which the tender-mouthed gazelles had spared w r as immediately devoured by some larger, 
more hardy, wild animal, it has become clear to me why, as far as the eye could reach, only tough prickly 
grasses, thorny briars, thistle flowers and inedibly bitter wormwood or acrid salt-plants were to be seen. 
It was also clear to me how this terrible warfare which the vegetation had to wage against its destroyers 
must influence the insect fauna, particularly the Lepidoptera. An almost complete absence of the monophagous 
leaf-feeders which have not selected thorny or poisonous plants as their food was a necessary consequence 
of it; also the wide distribution of those inhabitants of the steppes which can endure long seasons of drought: 
a preponderance of those forms which fly in one very short generation or which in a second generation 
are adapted to quite different conditions of vegetation and weather, etc. I might even say that there is 
hardly any fauna in the world whose peculiatities are derived so naturally from the character of their native 
land as the African; and these peculiarities we will endeavour to bring out in the following lines. 
A universal distribution of many species within the Ethiopian Region, which extends over almost 
the entire continent, is the most prominent peculiarity. In no other fauna does it happen to the same 
extent that a butterfly (say for instance for Africa Dunais chrysippus , Pyraineis cardui, Lycaena baetica, 
Deiopeia pulcliella, Catopsiliu florella, Celerio celerio, and many others) is found approximately as commonly at 
the north as at the south boundary, in the extreme west as in the east of the region. 
Strongly developed polymorphism is a further characteristic. Hence it is that many species vary 
according to sex as well as season, and further according to locality. Many species have for both cf and ? 
a characteristic form for the rainy as well as for the dry season, so that for every locality of the Ethiopian 
fauna many species occur in 4 clearly distinguished forms. Sometimes these forms alter completely even 
in adjacent districts, and this explains why sometimes over 30 species have been erected for what we now 
regard as forms of a single one. 
Mimicry also is here at work, and in a form thoroughly characteristic of Africa. We have the 
so-called »Uniforms« here also, as we made acquaintance with them in America for instance. Models are 
principally the At murk- species and the Acraeids. But together with this the sovereign disregard of proportion 
in size is truly African. Ear more than is the case in any other region, we find undoubted imitations and 
similarities in colour and pattern where the size is so entirely different that we might regard any effective 
deception as a priori out of the question; but he who knows the African fauna accurately considers this 
deception as not out of the question, but as intended by nature, and as very feasible, for the following reasons. 
In a survey of extensive African material we meet with a great richness in dwarfed and crippled 
forms. Large, deep-coloured and strongly-built wet-season forms may have tiny, pale-coloured and almost 
patternless butterflies as dry forms. Thus 1 observed in my daily excursions how the individuals of a species 
