MANNER OF DEVELOPMENT. 45 



Various other anomalies in man, more or less analogous 

 to the foregoing, have been advanced by different authors, 

 as cases of reversion ; but these seem not a little doubtful, 

 for we have to descend extremely low in the mammalian 

 series, before we find such structures normally present.* 



In man, the canine teeth are perfectly efficient instruments 

 for mastication. But their true canine character, as Owenf 

 remarks, " is indicated by the conical form of the crown, 

 which terminates in an obtuse point, is convex outward 

 and flat or sub-concave within, at the base of which surface 

 there is a feeble prominence. The conical form is best ex- 

 pressed in the Melanian races, especially the Australian. 

 '^ The canine is more deeply implanted, and by a stronger 

 fang than the incisors.'^ Nevertheless, this tooth no longer 

 serves man as a sj^ecial weapon for tearing his enemies or 

 prey ; it may, therefore, as far as its proper funtion is con- 

 cerned, be considered as rudimentary. In every large col- 

 lection of human skulls some may be found, as HackelJ 

 observes, with the canine teeth projecting considerably be- 

 yond the others in the same manner as in the anthropomor- 

 phous apes, but in a less degree. In these cases, open 

 spaces between the teeth in the one jaw are left for the re- 

 ception of the canines of the opposite jaw. An interspace 

 of this kind in a Kaffir skull, figured by Wagner, is sur- 

 prisingly wide. Considering how few are the ancient 

 skulls which have been examined, compared to recent 

 skulls, it is an interesting fact that in at least three cases 



* A whole series of cases is given by Isid. Geoffroy St.-Hilaire, 

 " Hist, des Anomalies," torn, iii, p. 437. A reviewer (" Journal of 

 Anat. and Physiology," 1871, p. 366) blames me mucli for not having 

 discussed the numerous cases, which have been recorded, of various 

 parts arrested in their development. He says that, according to my 

 theory, " every transient condition of an organ, during its develop- 

 ment, is not only a means to an end, but once was an end in itself." 

 This does not seem to me necessarily to hold good. Why should not 

 variation occur during an early period of development, having no 

 relation to reversion ; yet such variations might be preserved and ac- 

 cumulated, if in any way serviceable, for instance, in shortening and 

 simplifying the course of development ? And again, why should not 

 injurious abnormalities, such as atrophied or hypertrophied parts, 

 which have no relation to a former state of existence, occur at an 

 early period, as well as during maturity ? 



f "Anatomy of Vertbrats," vol. iii, 1868, p. 323. 



X " Generelle Morphologie," 1866, B. ii, s. civ. 



^Carl Vogt's "Lectures on Man," Eng. translat., 1864, p. 151. 



