528 



EVOLUTION, HEREDITY, EUGENICS 



functional in the herbivores, is a menace to the health of man. A 

 little blunt point projects from the inwardly folded margin or helix 

 of the ear. It is the vestige of the point in lower animals. A tiny 

 third eyelid is still found in man. Adult man has rudimentary hairs 

 over most parts of the body. At the sixth fetal month the fetus 

 has long hair over the body — " lanugo " — which in most cases is 

 shed before birth. 



Evidence from Blood Tests. Precipitation Method. — Freshly 

 drawn human blood is allowed to clot, then the serum drawn away. 

 Small quantities of the serum are injected at intervals of one or two 



days into the veins of a rabbit and 

 cause the formation in the rabbit's 

 blood of an antibody, analogous to 

 antitoxin obtained from a horse after 

 injection of diphtheria virus. After 

 the last injection, the rabbit is al- 

 lowed to live several days, then is 

 bled and the serum drained off and 

 preserved. This is " anti-human " 

 serum and is a delicate test for hu- 

 man blood, not only when it is fresh, 

 but even when in the form of old 

 and dried blood stains. Into an 

 " unknown " solution of blood, a 

 few drops of the anti-human serum 

 are passed, and, if the stains are hu- 

 man blood, a white precipitate is 

 formed and thrown down, but if 

 the stains are of some domestic 

 animal — pig, sheep or fowl — no such 

 reaction (precipitation) occurs. This 

 test is used in the detection of crime. Nuttall and others have 

 shown that if sufficiently strong solutions be used and time enough 

 be allowed, a relationship between the blood of all mammals is 

 made evident. 



Nuttall says: " The evidence which I published upon my tests 

 with precipitins shows that reactions obtained with the blood of 

 Simiidae (Manlike apes) closely resemble those obtained with 

 human blood, the bloods of Cercopithecidae (Old World monkeys) 

 came next, followed by those of Cebidae and Hapalidae (New World 



F^MliK 



Fig. 265. Vestigial pelvic girdle 

 and hind limbs of the python. 

 (From Romanes, Darwin and After 

 Darwin. Courtesy of Open Court 

 Publishing Co.) 



