64 



DISCOVERY 



the property of tallness is handed down in sweet-pea 

 families. The most noteworthy, perhaps, is a con- 

 dition in which the blood of the person affected does 

 not readily clot, and these persons run a grave risk 

 even where a slight operation such as the removal of a 

 tooth is necessary. This state of affairs is known 

 as " Haemophilia," and, although everywhere rare, is 

 relatively common in Germany, and unknown in the 

 tropics. Males alone are affected, but females trans- 

 mit this peculiarity ; before the war many of the 

 royal families of Europe had " haemophiliacs " among 

 their number. 



Other such conditions are colour-blindness — also 

 more common in men than women, and transmitted 

 through women ; night-blindness, and other forms of 

 abnormal eyesight. 



The presence of any of these conditions in a child 

 would be strong evidence of relationship to a sup- 

 posed parent who also manifested the peculiarity. 

 But all of them are rare ; some of them — for example, 

 the condition in which blood does not clot— do not 

 appear until a child is two years old ; and colour- 

 blindness is a feature which it would be difficult to 

 establish in a court of law. These facts render the 

 possible usefulness of arguments based on such inherited 

 characters rather small. We obviously require a 

 hereditary characteristic which is common to all men, 

 but capable of some degree of variation. 



It is suggested by Dr. S. C. Dyke ' that we have 

 such a test of relationship in certain peculiarities of the 

 blood. For many years it has been recognised that 

 when it becomes necessary to transfuse blood from a 

 healthy person to one who has lost a great deal, care 

 must be taken lest the remedy be worse than the 

 disease. The blood of some people is not compatible 

 with that of others, and fatal results have occurred. 

 Investigation shows that these accidents are due to the 

 fact that the clear fluid of the blood of some people 

 has the property of making the red blood cells of other 

 people collect together in colonies. 



A simple test has been devised whereby we can 

 group individuals under one of four classes according 

 to the reaction of their blood cells to the clear fluid 

 of other individuals. In England a large proportion 

 of the population comes under the same group, but as 

 one travels cast, the proportion gradually changes, 

 until the group most strongly represented in England 

 is least represented in India. In fact, researches have 

 been undertaken with a view to determining the 

 origins of nations and their varied constituent races 

 by this test. 



It appears that in these groups we have character- 

 istics which, unlike red hair or eye colour, can really 

 guide us to a decision on the point of parentage. For 

 • Lancet, December i6, 1922. 



example, if both parents belong to Group 2, the chil- 

 dren must belong to Group 2 or Group 4 ; if a child 

 belongs to Group i or Group 3, it is not the child of 

 these parents. 



However, the application of this test is only a 

 limited one. In the first place, one of the groups, 

 as has been mentioned, is scantily represented in 

 England, and this fact narrows the possibilities of the 

 case greatly. Again, the majority of legal cases of 

 this nature involve a position where one parent is 

 acknowledged, and the only question concerns the 

 other. In such circumstances the possibility of a 

 decisive result is small. But if it proves of use in 

 only a few cases, it wiU provide an answer to one of the 

 most tangled questions which come up for decision 

 in the courts of law — provided always that the legal 

 mind, with its cautious prejudice against scientific 

 proof, can be brought to accept it. 



Oxygen and Violent 

 Exercise 



By A. V. Hill, Sc.D., F.R.S. 



Professor of Phijsinlogy in the Uriiuersily of Muiichester 



A LIVING body, even a piece of isolated muscle, is never, 

 chemically speaking, " at rest." Apart from move- 

 ment of any kind, an incessant progress of chemical 

 change is necessary, to maintain that state of organisa- 

 tion of molecules, of readiness and power to react to 

 a stimulus, which is regarded as one essential property 

 of life. This chemical change is sometimes of an 

 upward or constructi^'e type in \vhich complex bodies 

 are made from simple ones ; chemical energy can then 

 be stored at the expense of energy from without. 

 But at other times life is accompanied by a downward 

 or destructive change in which the chemical energy 

 previously stored is degraded. In the muscle of a 

 frog, which by suitable treatment may be kept " alive " 

 (in the sense that it will contract when excited) for as 

 long as a month after removal from the body, there 

 is a continual evolution of heat, a production of the 

 gas carbon dioxide, and a utilisation of oxygen. This 

 heat is given out at the rate of about three-tenths of 

 the ordinary unit of heat (the gram-calorie) per hour 

 for everj' gram of muscle when the muscles are kept 

 at about 15° C, is greater when the temperature is 

 higher, and less when the temperature is lower, being 

 increased (or decreased) two or three times by a rise 

 (or fall) of ten degrees. Now it is well known to 

 chemists that the rate at which a chemical reaction 

 goes is similarly affected by a rise or fall of tempera- 



