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elxii 
sheep and goats which browse on the scanty vegetation. 
Where the ground is scoured by the flocks from time to time, 
no luxuriant vegetation has any chance, and only plants 
protected by long sharp spines, like Zizyphus, can withstand 
the ruminants and form low sparse clumps of scrub. The 
nomads trek with all their belongings from pasture to pasture 
and when in the spring the weather gets hot and the feeding 
grounds of the Sahara begin to dry up, large caravans pour from 
the desert on to the High Plateaux through the passes of the 
Southern Atlas, and during the summer the Plateaux have to 
support all this cattle from the desert in addition to the herds 
of the natives and Europeans who have permanently settled 
on the Plateaux. The effect on the vegetation is not difficult 
to imagine nor difficult to ascertain. Seeing the crowds of 
sheep and goats on the waste lands of the High Plateaux one 
wonders that these herds find food enough on the pebble- and 
rock-strewn hills and that any plants can recover, though their 
roots may run deep down in the crevices of the rocks. The fact 
is that in years of exceptional drought the herds don’t find 
pasture and the cattle perish by the thousands, as in 1919 and 
1920, when in places the nomad took again to brigandage as 
in olden times in order to save his life. Nature revenges itself 
on a state of civilisation which is stagnant and remains in the 
old channels when the larger population, larger flocks, re- 
claiming of arable land by new settlers who introduce new 
implements and altogether new conditions of life, demand 
adaptation to these altered circumstances. That applies not 
only to the nomad of the desert, but with him the matter 
will soon become acute when agriculture and afforestation 
is more extensively taken in hand on the High Plateaux; then 
the summer pasture grounds of the Nomads of the Algerian 
Sahara will be no longer available for him. 
I will now conclude this address, which had to be of a some- 
what cursory nature. It is, as it were, an excursion into a 
country full of interest for the naturalist, and as on an 
excursion one does not see everything or catch every species 
there may be, I trust you will forgive me for omitting 
many points of importance, I thank you very much for 
listening to me patiently. 
