68 THE ROYAL SOCIETY OF CANADA 



strangely leaves out a lot which seem equally important, and thus 

 the epitome is not ideally perfect and comprehensive. But taking 

 the law in its general sense and as it applies to the question under 

 consideration, its validity is unassailable and it reveals to us many 

 important truths. Thus we learn, for example, that in the later 

 stages of embryological development the apes and man follow par- 

 allel lines which are practically indistinguishable and that during this 

 stage there is a much closer resemblance between the two in the facial 

 and cerebral portions of their heads than appears later in post-natal 

 life. In both we see the same simple generalised head-form, each 

 being equally lacking in any specialised feature. After birth the 

 skulls of the human young retain this generalised form longer than 

 do those of the young of the apes who are seen to more quickly take 

 on the cranial characters of the typical mature human skull as they 

 pass on to the specialised form of their parents, as may be seen 

 from the comparison of skulls in Figure 5. 



Now it must follow from Baer's law that the skull-forms of the 

 young of the anthropoids and the young of man must represent very 

 closely the original skull-form of their common progenitor; so that 

 if we were to take a composite photograph of a series of both forms 

 the result would be a type of skull that represents as closely as can 

 be the actual head or skull-form of Homosimius precursor. 



Are we not, then, forced by the cogency of these facts, to conclude 

 that man has differentiated little in respect to his skull-form, while 

 the anthropoids have differentiated much; and that consequently 

 Pithecanthropus and Neanderthal man do not truly represent in 

 their cranial characters man as he was under his primitive aspects, 

 but rather those anthropoids which have diverged least from the 

 ancestral form; and that in the men of the Mousterian epoch we see 

 the same tendency toward that facial and cranial musculature which 

 is characteristic of the mature anthropoids and which has resulted 

 in giving them their present head-forms? 



This view is further supported by the cranial characters of the 

 Anthropoidea as a whole. Any one who has observed the young of 

 monkeys, both of the Old and the New Worlds, will be aware that 

 they show a much closer resemblance to the human type, both in 

 facial and cranial characters, than do their parents. The human 

 aspect of some of them is truly remarkable, and this resemblance grows 

 less and less as they mature and take on the specialised characters 

 of their species, thus confirming the truth of Baer's biogenetic law. 



Viewing Mousterian man in this light and as one of the several 

 species or genera into which early man became differentiated we can 



