1301 



VARIETIES OF MANKIND. 



first time they are taken to the woods, are 

 acquainted with this mode of attack ; whereas 

 a dog of another breed starts forward at once, 

 is surrounded by the peccari, and, whatever 

 may be his strength, is destroyed in a moment. 

 The fixed and deliberate stand of the pointer, 

 again, whether taught by the agency of man, 

 or a habit engendered, like the preceding, by 

 the force of circumstances, is so intimately con- 

 nected with the constitution of the race, that 

 occasionally it becomes hereditary ; a young 

 pointer, taken into the field for the first time, 

 being often observed to perform its duty 

 as well as its long-trained seniors. A still 

 more remarkable example of the transmission 

 of acquired psychical peculiarities, is afforded 

 by the case of the retriever, a breed of dogs 

 which has been trained to keep close to the 

 sportsman until he has fired, and then to go 

 in search of the game which he has wounded 

 or brought down. It is obvious that this 

 habit could only have been taught by the 

 agency of man ; and yet it has been frequently 

 observed that a young retriever, on the very 

 first occasion of being taken into the field, 

 has conducted itself as well, and brought back 

 game with as much steadiness, as older dogs 

 which had been schooled into the same ma- 

 noeuvre by means of the whip and collar.* 



No really philosophical botanist or zoolo- 

 gist, then, should venture to establish specific 

 distinctions between two races, otherwise 

 than provisionally, until he has been able to 

 assure himself that the one may not be con- 

 verted into the other by a change in external 

 conditions. Characters which are of the 

 most trivial kind in themselves, may be valid 

 grounds of specific distinction, if they are not 

 liable to be thus affected ; on the other hand, 

 characters which would be accepted in one 

 group as sufficient for the separation of ge- 

 nera, may be found totally inadequate in an- 

 other for the discrimination of species, being 

 liable to modification under a very slight 

 change of external conditions. Every one is 

 familiar with the changes which have been in- 

 duced in plants by cultivation, how a " sin- 

 gle " flower is converted into a " double " 

 one ; how the spines, prickles, and thorns 

 covering the surface may be obliterated (a 

 change which was fancifully, but not impro- 

 perly, termed by Linnaeus ** the taming of wild 

 fruits ") ; and how the wavy leaves may be- 

 come thick and fleshy (as in the change of the 

 Brassica oleracea into the cabbage), or the 

 slender flower-stalks may be converted into a 

 substantial mass (as in the conversion of the 

 same plant into the cauliflower). These 

 changes do not, as some have alleged, throw 

 the least doubt on the " permanence of spe- 

 cies," or favour the doctrine of " transmuta- 

 tion " in the slightest degree ; for however 

 wide may be limits of variation, each species 

 has its limits; and so far from having per- 

 manently advanced, under the influence of 



* See Mr. P. A. Knight's Paper on the Heredi- 

 tary and Acquired Instincts of Animals, in the Phi- 

 losophical Transactions for 1837. 



cultivation, to a superior type of structure, the 

 plants thus modified will all return to their 

 original form, when subjected to their original 

 conditions. Numerous instances might be 

 cited from the British Flora alone, in which 

 the most experienced botanists are in dis- 

 agreement upon the question of specific unity 

 or diversity, simply because they have not yet 

 ascertained the limits to the variations which 

 the same plant may present, when growing 

 under a variety of external conditions ; and 

 the difficulty is yet greater when British and 

 Continental species are compared, the variety 

 of external conditions being greater, and the 

 amount of allowance which should be made 

 for their influence being known in but a few 

 cases. The same may be said of Animals ; 

 particularly of those on which the influence 

 of domestication has been brought to bear. 

 Upon this point, however, we shall defer en- 

 larging, until the next head of the inquiry has 

 been considered. 



3. A tendency to variation exists in many 

 races, which manifests itself rather in modi- 

 fications of the specific type presented in the 

 course of successive generations, than in the 

 alterations induced by external agencies in 

 the individuals of one generation. Thus we 

 find that the offspring of any one pair do not 

 all precisely agree among themselves, or with 

 their parents, in bodily conformation or in 

 psychical character ; but that individual differ- 

 ences (as they are termed) exist among them. 

 Now, as this tendency to variation cannot be 

 clearly traced to any influence of external cir- 

 cumstances, it is commonly distinguished by 

 the term ' spontaneous ; ' but there is much 

 to favour the belief, that such variations are 

 attributable to agencies operating either on 

 both parents, previous to their intercourse, 

 or at the time of coition, or to influences 

 acting on the female during the period of 

 utero-gestation.* For it may be uniformly 

 observed, that those animals exhibit the 

 greatest tendency to this ' spontaneous ' va- 

 riation, which present the greatest constitu- 

 tional adaptiveness to a variety of external 

 conditions. And there are many cases in 

 which it seems pretty clear, that the cause of 

 this variation must be looked for in that com- 

 bination of influences, which is known under 

 the general term domestication. Thus it may 

 be stated as a general fact, that the varieties 

 of colour so remarkable in domesticated races, 

 tend to disappear when these races return in 

 any considerable degree towards their primi- 

 tive wild state. This has been especially 

 noticed in the horses, cattle, sheep, hogs, and 

 dogs, introduced by the Spaniards into South 

 America ; and the observation has been con- 

 firmed in other parts of the globe, showing 

 that there is nothing peculiar to the climate 

 of that country, which brings about the altera- 



* As these modifications are witnessed in domes- 

 ticated birds no less than in mammals, it is obvious 

 that the latter source of influence is excluded in 

 their case ; and we must fall back upon the pro- 

 bability of a change in the constitution of the pa- 

 rents, previously to the generative act. 



