ON OUR PRESENT KNOWLEDGE OF THE ORIGIN OF MAN. 4(55 



rise to a height of organization that makes clear as day the immediate 

 transition to the human form. For that reason one of the most pro- 

 found students of the anatomy of primates, Robert Hartmann, went 

 so far as to separate the entire order of primates into three families: 

 (1) Primarii (man and the anthropoid apes); (2) Simice, or apes proper 

 (catarrhines and platyrrhines); (3) Prosimice (lemurs). This arrange- 

 ment seems justified by the interesting statement made by Selenka 

 (1890) that the quite peculiar formation of the placenta of man is found 

 in the anthropoids, but not in the other apes. 



Decisive for the question as to which of these various classifications 

 we should prefer was the proposition advanced by Huxley, in 1S63, 

 after a careful and critical examination of all the anatomical relations 

 within the order of primates, and which I have called in his honor 

 u Huxley's law," or Huxley's pithecometric proposition: '■ Whatever 

 system of organs be studied, the comparison of their modifications in 

 the ape series leads us to one and the same result — that the structural 

 differences which separate man from the gorilla aud the chimpanzee 

 are not so great as those which separate the gorilla from the lower 

 apes." Thereupon it becomes necessary for every unprejudiced tax- 

 onomist to give man a systematic place within the order of the apes. 

 By the most conscientious testing of each difference, and by the most 

 severe logical inference, we can, however, go a step further and 

 instead of using the wider term apes (Simice), use the more restricted 

 one of Old- World apes (GatarrMnce). The standard pithecometric 

 proposition would then be worded in this more exact way: " The com- 

 parative auatomy of all organs within the catarrhine group leads us to 

 one and the same result — the morphological differences between man 

 and the anthropomorphous Old- World apes are not so great as those 

 which separate these anthropoids from the papiomorphous baboons, 

 the lowest of the catarrhines." 



We can now immediately utilize this incontestable pithecometric 

 proposition, both for firmly establishing the basis of the systematic 

 classification of the primates and for the genealogy of man. For the 

 natural system is, within the order of the primates, an expression of 

 genealogical relationship, just as it is in every other group of the ani- 

 mal aud vegetable kingdoms. Hence result the following important 

 inferences as to the genealogical tree of man: (1) The primates form a 

 natural monophyletic group; all "dominant animals," lemurs, apes, 

 and man himself sprang from a common original stem form, a hypo- 

 thetical ArcMprimas. (2) Of the two orders of the legion of the pri- 

 mates the lemurs are the lowest and oldest; from them, later, the true 

 apes (Simice,) first developed. (3) Among these latter the Old- World 

 apes form a natural monophyletic group; their common hypothetical 

 stem form (Archipithecus) is, directly or indirectly, derived from a 

 branch of the lemurs, no matter what relation they may be assumed 

 to have to the New- World apes. (4) Man is descended from a series 

 S M 98 30 



