Birds as Destroyers and Distributers of Weed Seeds. 75 

 Greenfinch. 



Kerner (79) remarks that: " The modes of dispersion of fruite 

 and seeds through the agency of animals are almost as varied as the 

 different methods of dissemination by the wind. In many oases such 

 dispersion is brought about by the animals using the fruits and seeds 

 in question for food ; the undigested parts are excreted, and any 

 embryos which may have survived the passage through the alimen- 

 tary canal subsequently germinate." As the fact of this mode of 

 dispersion has been a matter of dispute amongst botanists, and could 

 only be established by experiment, Kerner determined to feed various 

 animals with selected fruits and seeds, and to ascertain, first of all, 

 whether the embryos preserve their vitality after passing through an 

 animal's intestinal canal. For this purpose he took fruite -and seeds 

 belonging to two hundred and fifty different species of plants and 

 fed them to the following birds: 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. 

 ' The faeces were examined 'after each meal, 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 neces- 

 sary to take in conducting these laborious researches ; a statement, 

 however, of the most important results obtained from five hundred 

 and twenty separate experiments will suffice for our purpose." 



The birds resolved themselves into three groups in relation to 

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

 up even the hardest fruits and seeds in their muscular gizzards, 



