14 



INSTINCT. 



height of from twelve to fifteen feet, and so 

 clear the cataract that impedes their course ; 

 if they fail in their first attempt, they continue 

 their efforts till they have accomplished it. 

 The female is stated to hollow out a long and 

 deep excavation in the gravelly bed of the river 

 to receive her spawn."* 



A similar periodical emigration has been ob- 

 served in other animals, particularly in some of 

 the Crustacea. 



" Several of the crabs forsake the waters for 

 a time, and return to them to cast their spawn ; 

 but the most celebrated of all is that known 

 by the name of land-crab, and alluded to by 

 Dr. Paley as the violet-crab, and which is 

 called by the French the tourlounm. They are 

 natives of the West Indies and South Ame- 

 rica. In the rainy season, in May and June, 

 their instinct impels them to seek the sea, that 

 they may fulfil the great law of their Creator, 

 and cast their spawn. They descend the moun- 

 tains, which are their usual abode, in such 

 numbers that the roads and woods are covered 

 witli them." " They are said to halt twice every 

 day, and to travel chiefly in the night. Arrived 

 at the sea-shore, they are there reported to 

 bathe three or four times, when retiring to the 

 neighbouring plains or woods, they repose for 

 some time, and then the females return to the 

 water, and commit their eggs to the waves. 

 This business dispatched, they endeavour to 

 regain, in the same order, the country they had 

 left, and by the same route, but only the most 

 vigorous can reach the mountains. "f 



The object of all these migrations is, that the 

 female animals may have an opportunity of de- 

 positing their eggs where they will be in circum- 

 stances suited to their development, particularly 

 as to the essential requisites, exposure to heat 

 and to air. 



2. The same object, the choice of a suitable 

 place for depositing their eggs, is accomplished 

 in other instances by very different instincts im- 

 planted in female animals. " Repiiles," says 

 Kirby, " and Fishes do not feel the instinctive 

 love for their young, after birth, which is ex- 

 hibited by quadrupeds and birds, but are in- 

 variably instructed by the Creator to select a 

 place in which their eggs can be hatched either 

 by artificial or solar heat." Many of them 

 likewise, as the salmon, dig holes before 

 depositing them, for their protection. Those 

 of the serpents which are not ovo-viviparous, 

 bury their eggs in sand, or in heaps of fer- 

 menting matter. The Saurians also select a 

 proper place for their eggs, the crocodile, e.g. 

 the sands beside rivers ; " one species of sala- 

 mander commits a single egg to a leaf of 

 Persicaria, protects it by carefully doubling the 

 leaf, and then proceeding to another, repeats 

 the manoeuvre till her oviposition is finished. 

 Toads and frogs lay their eggs in water, sur- 

 rounded by a gelatinous envelope which forms 

 the first nourishment of the embryo," corres- 

 ponding to the albumen of the bird's egg. 



In like manner every insect is directed by 

 nature to place its eggs in situations where its 



Kirby, vol. i. 



t Ibid. 



young, when disclosed, will find its appro- 

 priate nourishment ; some burrowing in the 

 earth for this purpose ; many flies in dead 

 animal matter about to putrefy ; many in dif- 

 ferent parts of living vegetables;* bees and ants 

 in the cells where they are to be fed by the 

 working members of their hives, &c. A spe- 

 cies of the ichneumon fly and some of the 

 wasps have been observed to bury caterpillars 

 along with their eggs, on which their larvae 

 are to feed, and another fly to deposit its eggs 

 on the back of a caterpillar, when the larvae 

 feed on the secretion by which the covering of 

 the pupa is to be formed.f 



3. The instincts called into action in the 

 nidification, particularly of birds, are so nume- 

 rous, varied, and admirably adapted to their 

 purpose, as to have called forth admiration in all 

 ages. The pairing of the parent birds at the 

 beginning of spring, when the labour is to 

 begin ; the choice of a place suited to the 

 habits of the species, on the ground, under 

 ground, in rocks, on the edge of lakes or of 

 the sea, in marshes, in bushes, on trees, on 

 buildings of all descriptions ; the choice of the 

 materials, and the labour exerted for com- 

 pleting the work ; some using clay, some sand, 

 some moss, some leaves, some straw or twigs, 

 some moss or lichen ; many forming a rough 

 outside of materials hardly to be distinguished 

 from the surrounding objects, while the inside 

 is warm and smooth ; some building in very pe- 

 culiar forms to impede the access to their young ; 

 the tailor-bird sewing leaves together with 

 distinct stitches, and the Java swallows forming 

 their gelatinous nests, as the bees manufacture 

 their waxen cells, from the contents and secre- 

 tions of their own stomachs ; all furnish proofs 

 of contrivance too obvious and too nearly ad- 

 justed to varying circumstances, to have es- 

 caped the attention even of careless observers. 

 Many of the Mammalia make some kind of 

 provision, although less artificial, for the re- 

 ception of their progeny. " Cats search about 

 inquisitively for a concealed situation ; bur- 

 rowing animals retire to the bottom of their 

 burrows, and several of the Rodentia make 

 beds of their own hair to receive their young ; " 

 all beasts of prey, whose progeny come into 

 the world blind and helpless, have some kind 

 of retreat in which they supply them at once 

 with warmth and nourishment. Many insects, 

 also, besides those which associate in hives, 

 use various precautions for the covering and pro- 

 tection of their eggs. 



4. The instinct of incubation, which forms 

 the next part of the provisions for the repro- 

 duction of birds, the extraordinary change then 

 effected in the habits of the female bird, par- 

 ticularly when attended and cheered, as hap- 

 pens in so many cases, by the equally temporary 

 instinct of song of the male bird, is another 

 natural phenomenon too striking and interesting 

 to have escaped observation ; and the object of 



* In this choice insects seem to be guided by the 

 sense of smell, at least in the case where the food 

 of the larvae to be brought forth is different from 

 that of the parent. 



t Darwin. 



