828 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS. 



which numerous spores are imbedded. This fluid gives off a far-reaching carrion 

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

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

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

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

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

 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-larvee. Frequently as soon as the receptacles appear above the 

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

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

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

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

 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 ofishoots is comparatively 

 seldom efi'ected by animals. Of the cases known the following are the most note- 

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

 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- 

 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 

 the bulbils of Polygonum viviparum and cranberries are the commonest food 

 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 

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

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

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

 process is really a mode of distributing the Polygonum, viviparum,. 



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

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

 Mamillarias (Mamillaria placostigma and gracilis) of the high mountains of Mexico. 



