Again, it may perhaps be said that leaf-eating forms are exceptional, and that therefore the struggle to attain high branches would not affect many Ungulates.

But surely, when these severe droughts necessary for the theory occur, the ground vegetation is supposed to be exhausted; and, indeed, the giraffe is quite capable of feeding from off the ground.

So that, in these cases, the other Ungulata _must_ have taken to leaf eating or have starved, and thus must have had any accidental long-necked varieties favoured and preserved exactly as the long-necked varieties of the giraffe are supposed to have been favoured and preserved.
The argument as to the different modes of preservation has been very well put by Mr.Wallace,[22] in reply to the objection that "colour, being dangerous, should not exist in nature." This objection appears similar to mine; as I say that a giraffe neck, being needful, there should be many animals with it, while the objector noticed by Mr.Wallace says, "a dull colour being needful, all animals should be so coloured." And Mr.Wallace shows in reply how porcupines, tortoises and mussels, very hard-coated bombadier beetles, stinging insects and nauseous-tasted caterpillars, can afford to be brilliant by the various means of active defence or passive protection they possess, other than obscure colouration.

He says "the {27} attitudes of some insects may also protect them, as the habit of turning up the tail by the harmless rove-beetles (Staphylinidae) no doubt leads other animals, besides children, to the belief that they can sting.

The curious attitude assumed by sphinx caterpillars is probably a safeguard, as well as the blood-red tentacles which can suddenly be thrown out from the neck by the caterpillars of all the true swallow-tailed butterflies." But, because many different kinds of animals can elude the observation or defy the attack of enemies in a great variety of ways, it by no means follows that there are any similar number and variety of ways for attaining vegetable food in a country where all such food, other than the lofty branches of trees, has been for a time destroyed.