DISPERSAL BY ANIMALS. 863 



the following birds were fed with them : blackbird, song-thrush, rock-thrush, robin, 

 jackdaw, raven, nutcracker, siskin, goldfinch, serin-finch, titmouse, bullfinch, cross- 

 bill, pigeon, fowl, turkey, and duck; and also the following mammals: marmot, 

 horse, ox, and pig. After each meal the faeces were examined, to ascertain what 

 seeds they contained, and were then laid on a separate bed of earth, and at the same 

 time fruits and seeds of the same plants which had not been used for food were 

 planted in an adjoining bed. It would be out of place to set forth here all the 

 precautions which it was necessary to take in conducting these laborious researches, 

 and I shall confine myself to a statement of the most important results obtained 

 from 520 separate experiments. 



As regards the mammals subjected to experiment very few words will sufiice. 

 A.lmost all the fruits and seeds administered to them, whether they took them 

 voluntarily or unawares mixed with their ordinary food, were destroyed either at 

 once or upon being chewed with the cud. It is true that a few millet-seeds germin- 

 ated from the ox-dung, and must therefore have escaped being crushed during 

 rumination, and that one or two solitaiy specimens of lentil-seeds and oat-fruits 

 similarly passed uninjured through a horse, whilst Comus alba, Hippophae rham- 

 noides, Ligustrum vulgare, Malva crispa, Rhaphanus sativus, and Robinia 

 Pseudacacia all germinated after passing through a pig; but the number of the 

 seedlings so obtained was scarcely appreciable as compared with the number of 

 fertile seeds swallowed in the animals' food, and the fruits and seeds of about 60 

 other species of plants completely lost all power of germination during their passage 

 through the intestines. The birds resolve themselves into three groups in relation 

 to the matter in question. The first group includes those which grind up even the 

 harde^ fruits and seeds in their muscular and hard-coated " gastric mills " which are 

 in addition usually filled with small stones and sand. Amongst these, some strip 

 the fruits and seeds when they first lay hold of them, and thereby condemn them to 

 destruction. To this group the following birds of those employed in the experi- 

 ments belong, viz. the turkey, the hen, the pigeon, the cross-bill, the bullfinch, the 

 goldfinch, the siskin, the serin-finch, the nutcracker, the titmouse, and the duck. 

 No seed capable of germination was found under ordinary conditions in the excre- 

 ments of these birds; only when on a few occasions food was forcibly administered 

 to the hen and to ducks, so that their crops must have been overloaded, were a few 

 seeds found to have escaped pulverization, and to still possess the power of develop- 

 ment. The seeds in question belonged to Arenaria serpyllifolia, Papaver Rhceas, 

 Sisymbrium, Sophia, Ribes rubruTHi, Ligustrum. vulgare, Fragaria Indica, and 

 other species. Ravens and jackdaws form a second gi'oup, in that the stones of the 

 drupes and hard-coated seeds of the berries which they ate passed uninjured through 

 the intestine, whilst soft-coated seeds and fruits were all destroyed. It is worth 

 mentioning in particular that after these birds had been fed with cherries their 

 excrements contained cherry-stones 15 mm. in diamater, every one of which was 

 able to germinate. Of the birds selected for experiment, the blackbird, the S(3ng- 

 thrush, the rock-thrush, and the robin belonged to a third group. Of these the 



