602 



SCIENCE 



[N. S. Vol. XXXVIII. No. 982 



highly pertinent to the thesis and its converse 

 or corollary, as worded above. This case is 

 that of the sucking lice (Pediculidse) of man, 

 the anthropoid apes and the tailed monkeys. 

 As no biting lice (Mallophaga) have been 

 found on man, nor on any anthropoid, and 

 only two species, so far, on the lower monk- 

 eys, no evidence from their distribution can 

 be derived to confirm or contradict the evi- 

 dence from the occurrence of the Pediculines. 



The situation is this. Sucking lice of spe- 

 cies representing two genera, Pediculus and 

 PMhirius, occur on man. Of the second 

 genus but one species is known, and this is 

 confined exclusively to Homo. Of the other, 

 Pediculus, six species (perhaps five and a va- 

 riety) are known of which two (or perhaps, as 

 Neumann holds, one and a well-marked va- 

 riety) occur on man and only on man, while 

 one is found, and exclusively, on the chim- 

 panzee, another on the gibbons (two species of 

 gibbons), and two on monkeys of an American 

 tailed genus, Ateles. On the other tailed 

 monkeys are found several Pediouline species 

 of two distinct genera, Pedicinus and PMhir- 

 pedecinus. 



It is gratifying — ^to the upholder of my 

 thesis — to find man and his cousins, the anthro- 

 poid apes, harboring and really characterized 

 by parasites of such near relationships, while 

 when the leap from the anthropoid to the lower 

 monkeys is made — a leap notoriously greater, 

 from a genetic point of view, than that from 

 man to the anthropoids — ^the parasites are 

 found to be of other genera. Only the Pedi- 

 culus species on Ateles seems to be a disturb- 

 ing exception. But it is precisely the monkey 

 genus Ateles which offers a special taxonomic 

 problem to students of the primates. Frie- 

 denthal (of serum precipitins fame) has af- 

 firmed that on a basis of blood and hair com- 

 parison Ateles shows unmistakable differences 

 from other tailed monkeys, and resemblances 

 with the anthropoids, and he suggests that in 

 Ateles we should see monkeys that, in a cer- 

 tain sense, replace, in the new world, the 

 anthropoids. 



The above is the situation as Fahrenholz 

 works it out. Neumann believes that the 



typical, man-infesting parasite species, Pedi- 

 culus capitis, should include not only the 

 other man-infesting form, P. corporis, but also 

 perhaps one of the Ateles-'vcdesting forms (P. 

 consohrinus) . And he is inclined to credit 

 Pediculus capitis with a tendency to pass 

 from man to man-apes and monkeys in me- 

 nageries, and to persist on these new hosts. If 

 capitis can do this, then that in itself is a 

 curiously strong indication of the genetic af- 

 finities of these various hosts, because both 

 the Mallophaga and Anoplura are curiously 

 sensitive to differences in host blood or host 

 hair and feathers. I have often become, in 

 the course of collection, the temporary host of 

 various bird- and mammal-infesting Mallo- 

 phaga, but these parasites all seemed as anxious 

 to escape as I was to have them. And they 

 did escape; or, if they did not, they died in a 

 few hours. There is, indeed, an extraordinar- 

 ily exact fitting of parasite to host in the case 

 of Mallophaga and Anoplura. It is hard to 

 understand of just what details this fitting 

 consists, beyond such more obvious, and in- 

 sufficient, ones, as number and shape of claws, 

 number and character of clinging spine-hairs, 

 etc. The essential fitting is far more subtle. 

 It is a fitting to the host's physiology as well 

 as to its epidermal structures. 



Anyway, Neumann has not known all the 

 cases of the taking of Pediculus specimens 

 from the man-apes and from Ateles, and some 

 of these cases are beyond the explanation of 

 casual straggling in menageries. For some of 

 the ape hosts were not in menageries. 



There is no doubt that man is host to cer- 

 tain permanent, wingless ecto-parasites which 

 find their closest relatives in parasites of the 

 man-apes and of a problematic lower monkey. 

 And this evidence from commonness of para- 

 sites adds itself to the already acquired great 

 mass of other evidence from conditions of 

 structure, blood serum reactions, erystallizable 

 proteins (hemoglobins), and the rest, that bind 

 us so unescapably in close genetic relationship 

 with the anthropoids. 



Vernon L. Kellogg 



Stanford Universitt, 

 California 



