HA RD WICKE ' S SCIENCE- G OS SIP. 



101 



the conclusion : " In order to maintain themselves 

 in due proportion they must bring forth a large 

 number of offspring so as to guard against the whole- 

 sale destruction of their young by their natural 

 enemies. The higher mammals are in a very large 

 measure exempt from this danger, and the necessity 

 for such an extraordinary fecundity as the Ichthyopsida 

 manifest is averted. Nevertheless by virtue of the law 

 of inheritance the ovary possesses an enormous 

 number of ova. Although mammals are thus spared 

 the trouble of bringing such large numbers of young 

 into the world, the suppression of ova acts as an 

 intrinsic source of danger, for these unused follicles 

 become in some instances the sources of ovarian 

 cysts, not in the human female only, but in the in- 

 dividual species throughout the kingdom mammalia. 

 It serves as an excellent instance of the application 

 of evolution to pathology." 



There is a zoological law, that the number of 

 mammce to any given animal varies in direct ratio to 

 the number of young which that animal produces. 

 Remembering this in conjunction with the evidence 

 given above, the only legitimate conclusion to come 

 to is that the suppression of ova in the fcetal ovary 

 and the occurrence of supernumerary mammse and 

 teats indicate an ancestry in which not only were 

 there a great number of offspring produced, but 

 also in which the females were assisted by the males 

 in giving suck to their young. 



There is a most pregnant utterance of Von Baer, 

 known it might be already to some readers. It is 

 thus : " The embryos of mammalia, of birds, of 

 lizards, and snakes, and probably also of Chelonia, 

 are in their earliest stages exceedingly like one 

 another, both as a whole and in the mode of develop- 

 ment of these parts, so much so, in fact, that we can 

 often distinguish the embryos only by their size." 

 And then: *' In my possession are two little embryos 

 in spirit, whose names I have omitted to attach, and 

 at present I am unable to say to what class they 

 belong. They may be lizards or small birds, or very 

 young mammalia, so complete is the similarity in the 

 mode of the formation of the head and trunk in these 

 animals. The extremities, however, are still absent in 

 these embryos. But even if they had existed in the 

 earliest stage of their development, we should learn 

 nothing, for the feet of lizards and mammals, the wings 

 and feet of birds,no less than the hands and feet of man 

 all arise from the same fundamental form." Hence the 

 enunciation of a law known from the days of this 

 father till now to hold in all perfectness — in the 

 words of Mr. Sutton — "that in the embryological 

 history of a given animal we read a brief epitome of 

 its ancestry — in fact its evolution." Professor Ernst 

 Haeckel has expressed it more fully, by putting it 

 thus and thus," Ontogenesis " (i.e. the development of 

 the individual) "is the brief and rapid recapitulation of 

 phylogenesis " (i.e. the development of the species) 

 "governed by the physiological functions of trans- 



mission and nutrition. The organic individual, during 

 the rapid and brief course of its individual development 

 repeats the most important of those changes of form 

 which its ancestors have passed through during the 

 long and gradual course of their palceontological 

 development in accordance with the laws of trans- 

 mission and adaptation." 



Next, let us look at those examples of atavism, or, 

 if you will, reversion to ancestral conditions, as 

 exemplified and enlarged upon by Mr. Sutton in his 

 lectures which form the subject of the present paper. 



Gegenbaur ("Polydactyly as Atavism," Morph. 

 Jahrb. Bd. vi. S. 584; also "J. Anat. and 

 Phys.," vol. xvi. p. 615), gives the following 

 caveat well shown in the case of the os centrale 

 above : " Atavism consists not in the existence of a 

 latent germ, but in its becoming perfected and further 

 developed." And moreover, Hensel, as well as this 

 last-named anatomist, utters further that, taking the 

 cases of reversion as a whole, the greater number of 



Fig. 4.-. 



Fig. 46. 



Fig. 45. — The nianus of Hipparion with three functional toes. 

 Fig. 46. — The manns of a horse with the medial digit functional. 



Afcer Marsh. 

 Fig. 47. — The nianus of the modern horse, one toe functional. 



"atavistic parts do not belong to forms palseonto- 

 logically remote or systematically far distant." This 

 too is illustrated by the selfsame os centrale, for it 

 obtains in the higher apes, as the ourang and gibbon. 

 But the best illustration perhaps is discovered in the 

 ancestor of our present horse. In the fauna of the 

 Pliocene epoch, one of the most abundant was an 

 animal somewhat of the size of a quagga, known as 

 Hipparion gracile, Gaudry ; this, the immediate 

 precursor of our old-world horse (Protohippus is the 

 representative of Hipparion in the new world 

 formations), had three digits, all of which were 

 functional, inasmuch as possessing well-developed 

 hoofs, and the evidence evinced by the case of the 

 Cuban horse to be presently described. The ulna 

 bone in Hipparion also was moderately well de- 

 veloped, a feature, which the anatomy of our own 

 horse is deficient, at any rate in adult life. Also 

 Hipparion in its distribution seems to have had a 

 wide radius, for it has been found in the Sewalik 

 hills in India as well as in the European strata. 



Go back still to the older Miocene epoch, and a 

 horse (Anchitherium) walked the earth with a well- 

 developed ulna and fibula, and with the three digits 

 all touching the ground. 



