828 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS. 



which numerous spores are imbedded. This fluid gives ofi" a far-reaching carrioi 

 smell which allures many insects, especially carrion-flies. The fact that the fluii 

 contains sugar which serves as nourishment for the insects also contributes to tht 

 allurement. A fly which alights on the cap of the Stink-horn cannot leave i 

 without spores adhering to its whole body. Some of them may, perhaps, fall of 

 while it is flying away, but the majority will not be brushed off" until it agaii 

 alights and cleanses itself from the uncomfortable appendages (c/. also p. 691). 



It is well known that the fleshy fructifications of Hymenomycetes provide food 

 for numerous insect-larvae. Frequently as soon as the receptacles appear above thef 

 soil the flesh of the stalk and cap are riddled by passages in which live the larvaes 

 of various gnats and beetles. These leave their dwellings before the decay and[l 

 decomposition of the Fungi set in, and enter the chrysalis stage in the ground. Inj 

 this way numerous spores which have adhered to the animals are carried awayj 

 and disseminated. The spores of various Fungi, especially of the Hymenomycetes! 

 and Truffles, are without doubt distributed by animals which eat the fleshy spore- 

 bearing portions. The spores pass unharmed through the alimentary canal and| 

 then germinate in the deposited excrement. Earthworms and swine in particular 

 seem to take part in this distribution. 



The dissemination of detached bud- and shoot-like offshoots is comparatively 

 seldom effected by animals. Of the cases known the following are the most note-t 

 worthy. First, where the offshoots are taken up as food by animals, but arej 

 again got rid of in an undigested condition, and grow up into new plants in the! 

 place where they have been deposited. This has certainly been observed in Poly- 1 

 gonum viviparum, which grows commonly in the far North and on the high^ 

 mountains of Central Europe (see fig. 452). The bulbils of these plants are a dainty ' 

 morsel to ptarmigan, and are eagerly sought for by them. The ptarmigan seizes 

 the lower half of the spike of the Polygonum with its beak, and by a quick 

 movement of its neck passes the bill the whole length of the spike, and so puts | 

 dozens of bulbils at a time into its crop. Numerous observations have shown that j 

 the bulbils of Polygonum viviparum and cranberries are the commonest food i 

 found in the crops of ptarmigan shot on the Alps, and I also always found these , 

 bulbils in great quantity in the crops of Norwegian ptarmigan. The portion which 

 passes from the crop into the muscular gizzard is of course crushed and digested, 

 but it has often been noticed that part of the food so greedily swallowed by the ; 

 ptarmigan is thrown up again, and this is particularly the case with the bulbils ( 

 when they have been taken in excess. When thus extruded, they have the power j 

 of further development; far from being destroyed, they grow up very rapidly into \ 

 new plants, and as the places where the superfluous food is thrown out are always I 

 at some distance from the spot where the ptarmigan obtained the bulbils, this | 

 process is really a mode of distributing the Polygonwm viviparum. I 



The second method of distributing detached offshoots by animals is effected by i 

 means of barbed bristles and hairs, such as are represented in fig. 457, in the i 

 Mamillarias {Mamillaria 'placostigma and gracilis) of the high mountains of Mexico. ^ 



