ADDENDA 



Note to page 23. — 



As a result of recent investigations on the sex chromosomes and 

 chromosome numbers in mammals, Theophilus S. Painter reaches the 

 conclusions that polyploidy cannot be invoked to explain evolution 

 within this class. After giving a table of chromosome numbers for 

 7 out of the 9 eutherian orders, Painter concludes: ''The facts recorded 

 above are of especial interest in that they indicate a unity of chromo- 

 some composition above the marsupial level and effectively dispose of 

 the suggestion that extensive polyploidy may have occurred within this 

 subclass. 



"In the marsupials the chromosome number is a low one and in the 

 opossum is 22. At first sight it might appear that the eutherian con- 

 dition might have arisen from this by tetraploidy. There are two ob- 

 jections, however. In the first place the bulk of the chromatin in 

 marsupials is about the same as in the eutheria, using the sex chromo- 

 some as our measure. In the second place, polyploidy could scarcely 

 occur successfully in animals with X-Y sex chromosomes, as most mam- 

 mals possess, because of the complication occurring in the sex 

 chromosome balance" (Science, April 17, 1925, p. 424). As the X-Y 

 type of sex chromosomes occurs widely not only among vertebrates, 

 but also among insects, nematodes, and echinoderms. Painter's latter 

 objection excludes evolution by polyploidy from a large portion of the 

 animal kingdom. 



Note to page 90. — 



Especially reprehensible, in this respect, are the reconstructions of 

 the Pithecanthropus, the Eoanthropus, and other alleged pitheco-human 

 link modeled by McGregor and others. These imaginative productions, 

 in which cranial fragments are arbitrarily completed and fancifully 

 overlayed with a veneering of human features, have no scientific value 

 or justification. It is consoling, therefore, to note that the great French 

 palaeontologist, Marcelin Boule, in his recent book "Les Hommes 

 Fossiles" (Paris, 1921), has entered a timely protest against the appear- 

 ance of such reconstructions in serious scientific works. "Dubois and 

 Manouvrier," he says, "have given reconstructions of the skull and 

 even of the head (of the Pithecanthropus). These attempts made 

 by medical men, are much too hypothetical, because we do not possess 

 a single element for the reconstruction of the basis of the brain case, or 

 of the jawbones. We are surprised to see that a great palaeontologist, 

 Osbom, publishes efforts of this kind. Dubois proceeded still farther 

 in the realm of imagination when he exhibited at the universal exposi- 

 tion of Paris a plastic and painted reproduction of the Pithecanthropus" 

 (op. cit., p. 105). And elsewhere he remarks: "Some true savants have 

 published portraits, covered with flesh and hair, not only of the 

 Neandertal Man, whose skeleton is known well enough today, but also 

 of the Man of Piltdown, whose remnants are so fragmentary; of the 

 Man of Heidelberg, of whom we have only the lower jawbone; of 

 the Pithecanthropus, of whom there exists only a piece of the cranium 

 and . . . two teeth. Such reproductions may have their place in works 

 of the lowest popularization. But they very much deface the books, 

 though otherwise valuable, into which they are introduced." . . . 

 "Men of science — and of conscience — know the difficulties of such at- 

 tempts too well to regard them as anything more than a pastime" 

 (op. cit., p. 227). 



Note to page 342. — 



A fourth possibility is suggested by the case of the so-called skull of 

 the Galley Hill Man, of whose importance as a prehistoric link Sir 

 Arthur Keith held a very high opinion, but which has since turned out 

 to be no skull at all, but merely an odd-shaped piece of stone. 



