522 



THE CAT. 



[CHAP. xv. 



cease, and, till death, the cat remains a cat simply. With, death, 

 however, the process of change recommences (though it is a very 

 different process), and continues during the gradual recession of all 

 those forms which have any relation to life, till the hody is reduced 

 to mere inorganic matter. 



12. According to our present experience then, we ought to 

 anticipate that any new ideal embodiment any new specific form- 

 would make its appearance during the period of embryonic life, and 

 that if a new cat-species is to appear, it will appear as a kitten 

 which differs more or less markedly from its parents. Such a birth 

 is by no means against experience. It is not merely that minute 

 changes occur no two individual animals being absolutely alike 

 but every now and then a marked variation takes place, as in the 

 case of the kitten seen by Mr. Birkett.* Such variations also are 

 capable of being transmitted to the offspring of the animals in which 

 they first arise. 



But we may even gather some evidence in favour of the origin of 

 species by considerable and not minute changes, from the special 

 subject of this work the group of Cats. Species of Machcerodus, like 

 Smilodon, were, as we have seen,f unable to kill by biting on 

 account of the enormous length of their upper canines, which could 

 only be used as daggers, the mouth being closed. All existing 

 feline animals, including the long-tailed, clouded tiger (F. macrocelis), 

 bite, and are unable to use their canines as daggers. Now, if the 

 canines of Machcerodus Smilodon had been formed by minute increase 

 in successive generations, the creatures would at one time have been 

 in a condition such that their teeth were too long to be conveniently 

 used for biting, while they were not yet long enough to be efficiently 

 used as daggers. It is true that there are different species of 

 Machcerodus with teeth of very different lengths, and it is also true 

 that before the canines became so long as to be quite useless for 

 biting, they would begin to be slightly useful as daggers. Still the 

 fact remains that a highly inconvenient transitional stage of exist- 

 ence J must have been passed through, if evolutionary changes were 



* See ante, p. 7. Amongst new organic 

 forms known to have been suddenly 

 evolved are : The black-shouldered pea- 

 cock, new forms of wild deer, a smooth 

 capsuled kind of Datura tatula, a com- 

 plex-capsuled form of poppy, &c., &c. 



f See ante, p. 432. 



t Professor Cope has said (see Pro- 

 ceedings of the Acad. of Nat. Sc. of 

 Philadelphia for July 8, 1879): "I 

 think there can be no doubt that the 

 huge canines in the Smilodons must 

 have prevented the biting off of flesh 

 from large pieces, so as to greatly inter- 

 fere with feeding. . . . The size of the 

 canines is such as to prevent their use as 

 cutting instruments, excepting with the 

 mouth closed, for the latter could not 



have been opened sufficiently to allow 

 any object to enter it from the front. 

 Even were it opened so far as to allow 

 the mandible to pass behind the apices 

 of the canines, there would appear to be 

 some risk of the hitter's becoming caught 

 on the point of one or the other canine." 

 As to the cause of the disappearance of 

 this highly specialized form of life, Pro- 

 fessor Flower has observed (in a lecture 

 delivered at the Royal Institution 011 

 March 10, 1876) : "It may have been 

 a case of over-specialization, in which 

 the development of the carnivorous type 

 of dentition, gradually accumulating in 

 intensity . . . , became at last a succes- 

 sive inheritance so exaggerated that its 

 growth outran its usefulness of purpose. 



