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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



Birds of the family of our cuckoo, spread through- 

 out the warm regions of Africa, Asia, and Austra- 

 lia, known under the name of " coucals," will give 

 us an instance of this. We know how flexible 

 and soft to the touch are the beards of the feath- 

 ers in the wings and tail of birds in general. 

 In these birds, on the contrary, they are stiff and 

 harsh like thorns. Without close observation, 

 much vain inquiry might have been spent as to 

 the necessity which this structure of the feathers 

 corresponded to ; but we had the notices of trav- 

 elers, and perceived at once a wonderful adapta- 

 tion. These birds live in gloomy forests, and feed 

 on insects, which they are obliged to pursue in 

 the thickets of vines twining about the trees. 

 These vines are extremely tough ; the ordinary 

 plumage of birds would be torn and cut to pieces 

 by the contact, but the feathers of the coucals 

 resist it. 



If we chose to pass in review the species of 

 birds, as to each one of them we should find in 

 the details of formation of the claws the signs of 

 certain habits easy to prove — in the shape and 

 development of the bill the mark of a preference 

 for some special kind of food. On this subject 

 a great number of curious observations are re- 

 corded which it is impossible for us to relate. 

 But here is one instance, taken almost at random 

 from among many others, of a very singular beak, 

 adapted to a very special kind of food, which 

 seems too instructive to be passed by. Every 

 one knows the crossbill, that prettily-feathered 

 bird which frequents forests of evergreen trees 

 and fir-plantations; its beak has the mandibles 

 very much arched in opposite directions, and 

 crossed for about two-thirds of their length. One 

 needs to see the bird provided with this strange 

 beak breaking and peeling the resinous cones, to 

 admire the usefulness of such an implement. A 

 very simple modification sufficed to create the 

 instrument with which it attacks the pine-cones, 

 and this sort of anomaly is produced only at a 

 late period in the animal's development. Is there 

 not here a fit subject to induce those naturalists 

 who have faith in the mutability of species to 

 try a little experiment ? It would merely be a 

 matter of shutting up a few crossbills in an in- 

 closure and depriving them of their usual food 

 while supplying them an abundance of the food 

 sought by granivorous birds. Either the cross- 

 bills would perish without breeding, or, as a re- 

 sult of their new food, after a few generations 

 their beak would have changed its shape and 

 taken another, better suited to a different kind 

 of life. If the experiment should succeed, our 



bird of the fir-groves would not yet have become 

 a common sparrow or an ordinary grossbeak, but 

 at least the theory that has made so much noise 

 would have gained one serious argument. 



Among fishes there are some kinds that seize 

 their prey in front of them, and even out of wa- 

 ter, and other kinds that seek their food in mud- 

 dy bottoms. With the first, as the perch, the 

 lower jaw projects beyond the upper ; with the 

 latter the contrary is the case ; the mouth is 

 crowded downward, and is often provided with 

 fleshy appendages fitted to stir up the mud : the 

 barbel is an instance of this. Thus everywhere 

 some characteristic points out habits and in- 

 stincts from which the animal cannot disengage 

 itself. 



With respect to insects and arachnids, the 

 study of coincidences between their ways and 

 their peculiarities of outward form has been car- 

 ried very far. The examination of the working- 

 tools in species fitted to build suffices now to 

 give us a certain conclusion as to the kind of 

 work the species performs. By the study of the 

 appendages we know in what way and under 

 what conditions the animal must move. In a 

 great variety of circumstances, from the ariange- 

 ment of the organs of sight, we infer, without 

 fear of mistake, the existence of wandeiing or 

 of sedentary habits, with a multitude of fine dis- 

 tinctions. At the same time, with insects and 

 arachnids we follow step by step, better, per- 

 haps, than in any other case, the advance in in- 

 stinct and intelligence with the growing perfec- 

 tion of the instruments, as also the diminishing 

 of these faculties along with the simplification 

 of the appendages. 



A different condition of abode from that usu- 

 ally presented to our notice offers considerable 

 interest with regard to the adaptation of organ- 

 isms to the media, and to the question of the 

 origin of beings. Animals of different classes 

 live in places wholly deprived of light ; these 

 animals are blind. Just a century ago there was 

 discovered in the subterranean waters of Lower 

 Carniola a sort of batrachian of pretty large size, 

 from eleven to thirteen inches long, of a pinkish 

 white, having external branchiae — in a word, re- 

 sembling, with larger proportions, the larva of a 

 triton or a water-salamander. The animal was 

 blind ; a zoologist introduced it by the name of 

 the " serpentine proteus." The first conjecture 

 was that this batrachian was carried into the 

 caverns by water overflowing in the rainy season 

 from the Sittich lakes ; but this supposition was 

 not found correct. The proteus has never been 



