98 ASSOCIATION OF ORGANISMS—THE WEB OF LIFE 
of Burdock (Arctium mazus, fig. 1088) cling with great tenacity 
to sheep and other animals. Each burr consists of a number 
of fruits enclosed by a great many narrow scales, each one of 
which is bent into a hook at its tip, A 
different but equally effective arrangement is 
present in Avens (Geum urbanum, fig. 1088). 
The group of fruits is not surrounded by 
clinging scales, but each is provided with a 
long hook. In some foreign fruits the hold- 
fasts are of formidable character, and cause 
much pain to the unfortunate animals which 
unwillingly promote dispersal. A well-known 
instance is that of the Harpoon-Plant (Har- 
pagophytum) of South Africa, the large fruits 
te which are covered with stout radiating pro- 
with Hooks: a few of the hooks, jections provided with powerful hooks. They 
are the source of much inconvenience to such 
animals as antelopes and lions, being said to sometimes cause 
the death of the latter. 
Dispersal of Spores by Animals.—Fleshy fungi are eaten by 
various insects that swallow vast numbers of the minute spores 
by which such plants propagate, 
these passing uninjured through 
their bodies. In some cases flies 
are attracted by a sweet fluid (as 
in Ergot, Claviceps purpurea), or by 
evil-smelling moisture that exudes 
on the spore-producing surface (as 
in the Stinkhorn, Phallus impudz- 
Fig. 1088.—Group of Hooked Fruits of Avens cus). Earth-Worms and other bur- 
flee ai Or iene sass payee oe soe 0 aoubt help “tp 
the Fruits of Burdock (Avctivm majus) surrounded isperse the spores of underground 
by hooked scales. : 
fungi, such as truffles. The last- 
named plants are also eagerly sought and devoured by pigs, with 
similar results. The dissemination by animals of disease-produc- 
ing bacteria is too notorious to require emphasizing. 
