HABITS OF STOCK WITH REFERENCE TO POISONOUS PLANTS. 33 



crop of leaves of foxglove {Digitalis jMirpurea) and henbane is infe- 

 rior to that of the second on account of the smaller quantit}^ of its 

 active principles and the larger quantity of water and other inert 

 compounds. The variation in strength of the powerfully poisonous 

 drug known as strophanthus is so well known to physicians that its 

 medical use is being abandoned. 



Many other instances of the variable location and quantitj^ of poi- 

 sonous substances in plants might be cited, but these will show the 

 importance of knowing the entire history of a plant in testing its 

 character as poisonous or nonpoisonous. 



VARIATIONS IN THE FEEDING HABITS OF STOCK WITH REFER- 

 ENCE TO POISONOUS PLANTS. 



A curious circumstance which one can not fail to observe in the 

 study of poisonous plants is the great variation in the ha])its of 

 domesticated animals with reference to eating them. This applies 

 both to different individuals of the same species and to the same indi- 

 vidual at different times. There seems to be no way of accounting 

 for the appetite or taste of stock. This statement is perhaps espe- 

 cially true of sheep. We have often observed sheep eating greedily 

 on one day plants which they could scarcely be persuaded to eat on 

 the following day on the same range. It is frequently to be observed 

 that one band of sheep eat f rceh' certain plants which are not touched 

 by another band of sheep feeding as nearly as possible under the same 

 conditions. It is also to be observed that there is a striking variation 

 in the taste of different sheep belonging to the same band. It is 

 manifestly not safe to conclude, when a certain number of sheep in a 

 given band are afl'gcted by a poisonous plant, that all of the sheep 

 have eaten the plant, and that the ones which are affected are the only 

 ones which are susceptible to the poisonous action of the plant. It 

 would be fully as safe to assume that the affected sheep alone ate the 

 plant in any appreciable quantity. Naturall}^ the variation in the 

 appetite and feeding habits of different sheep is not manifested merely 

 with reference to poisonous plants, but also to forage plants. 



It is rather an easy matter in observing the actions of a band of 

 sheep upon the range to note striking differences in the dietetic selec- 

 tions of different sheep. To illustrate, a few observations may be 

 recorded which were made upon a band of sheep on a foothill range 

 at an altitude of 4,600 feet. A few of the sheep were observed eating- 

 large quantities of wild sunflower {BalmmorMza sagittata)^ a few ate 

 freely of false lupine {T/ier/nopsis rhomhifolia), some confined their 

 attention largely to the wild geranium, ^v'hile others ate false esparcet 

 {Astragalus hisulcatus) almost exclusively. Two sheep were seen eat- 

 ing the leaves of lupine, and about fifty ate a greater or less quantity 

 of Zygadenuii venenosiu^. while the majority of sheep in the band fed 

 S. Doc. 160 3 



