ANIMAL-PLANTS AND PLANT-ANIMALS. 679 



out ; they then coat themselves with a crust of earth, and are depend- 

 ent on their lungs for every breath they draw. During the rest of the 

 year they can use either these or their gills. 



The close relation between fish and amphibia is established in yet 

 another way by the Caudata, which retains its gills and does not lose 

 them, as do its relatives, the frog and salamander. The olm of the 

 Adelsberg grottoes also belongs to this class ; it is an animal of a pale- 

 red color, which spends its existence in subterranean darkness. Its 

 eyes, as is also the case with other animals that live in constant dark- 

 ness, are not developed, there being no possible use to which they 

 could be put ; they are very small, and lie beneath the skin. 



A connecting link between the birds and the reptiles is found in 

 the fossil archaeopteryx brought to light in the slate-quarries at Soln- 

 hofen ; the feathers denote a bird, the rest of the body is that of a 

 reptile. The Omithorhynchus paradoxus of Australia serves to con- 

 nect the feathered tribe with the mammalia. It lives in seclusion in 

 dreary regions on river-banks, and builds its subterranean home in 

 such a manner that one of the two exits is always submerged by the 

 stream. It has four feet, and a broad bill, with horn plates on the 

 edges like that of the duck, and seeks its food like this fowl. At the 

 foot of the male there is a spur corresponding to that of a rooster ; 

 between the toes are webs like those of water-fowl. It would hardly 

 seem surprising to find this strange creature, in many respects so like 

 the birds, propagating its kind by eggs ; but it is a true mammal, and 

 gives birth to live young. 



The transition from the palms of the tropics to the palms of the 

 north — the fir-trees — is made by the shining cycadees, whose leaves, 

 as emblems of peace, are placed on tombs. The guetacea must also 

 be regarded as intermediate between the lower and the higher orders 

 of plants. To these belongs the curious " welwitschia " of Africa, the 

 thickness of whose stem exceeds by three times the height. During 

 its whole life — over a century in duration — it bears only two, but very 

 large, leaves, fully two metres in length and one metre broad ; it is 

 well named " the wonderful." 



At first sight the assertion may seem strange, that the dividing 

 line between the animal and the vegetable kingdom is not definite, 

 and that one may sometimes be in a quandary to know whether he is 

 dealing with an animal or a plant. That the rose must be accounted 

 a plant there can be no doubt ; and that the gaudy butterfly, coyly 

 hovering above it, must be classed with the animal kingdom, remains 

 unquestioned. But it is by no means so easy a matter to determine 

 the nature of that peculiar being which we find in damp moss. It is a 

 slimy mass, but little colored ; it moves slowly and in every direction, 

 yet no feet are discernible. After a long dispute the botanists have 

 had to accept into their realm these slime-fungi, for during a part of 

 their existence they are distinctively plants, and propagate by spores. 



