the animals affected were non-ruminants, while those not affected were ruminants. The probable explanation is that the ruminants, by thoroughly mixing the food with saliva and slowly digesting it, were enabled to neutralize the action of the poison and escape injury. The seeds probably contain the deleterious principle in a greater degree than any other part of the plant. It was a common experience that animals introduced from other localities suffered more than the native animals. The latter were either immune or had learnt to avoid the plant as noxious to them." That animals resident in a district are not poisoned by plants which are often fatal to sheep and cattle when on the march through it, has been often observed in Australia. The great "mobs" or droves of sheep passing slowly on their travels through the bush to a new district are often poisoned by the Caustic Creeper (_Euphorbia Drummondi_). "The head swells to an enormous extent, becoming so heavy that the animal cannot support it, and drags it along the ground"; but this does not apparently happen to resident cattle. Similarly for the Darling Pea or Indigo (_Swainsonia galegifolia_). At one place this was growing abundantly where some travelling horses were hobbled for the night. "They had been on the road some nine weeks, and were up to this date caught without any difficulty. On this occasion ... their eyes were staring out of their heads, and they were prancing against trees and shrubs.... When driven they would suddenly stop, turn round and round, and keep throwing their heads up as if they had been hit under the jaw.... Two out of nine died, and five others had to be left at the camp."[109] [109] _Plants Reputed Poisonous to Stock._ Bailey & Gordon, Brisbane. In other natural orders we find one or two dangerous plants amongst a whole series of perfectly harmless or useful forms. The Oleander, in the Olive order, Corncockle (_Lychnis floscuculli_), in the Pink order, _Lactuca Scariola_ amongst _Compositæ_ and others are all cases in point. So also is the Yew amongst _Coniferæ_, etc. How do animals recognize these particular plants as being dangerous whilst all their allies are harmless? But the reader will answer that they do not; it is well known that animals _are_ killed by eating poisonous plants, therefore poison cannot possibly be any protection against animals. This is one of those interesting questions in which the suppression of apparently irrelevant details produces confusion.