DOMESTIC ANIMALS 



35 



larly supposed that the imagination of 

 the mother, especially when stimulated 

 by fright or unusual experiences, may 

 exercise some mysterious effect on the 

 developing fetus. Innumerable sup- 

 posed cases of this kind have been re- 

 ported in man, farm mammals and 

 even in fowls. Children are said to 

 have been born with marks resem- 

 bling mice, goats, cows and other ani- 

 mals in consequence of their mothers 

 having been frightened by such animals 

 during their pregnancy. All sorts of mon- 

 strosities in offspring have been attrib- 

 uted to the influence of the imagination 

 of the female. One case is reported 

 where an Angus cow produced a black 

 and white calf with horns after having 

 seen a black and white horned steer. 



Perhaps the most astonishing case 

 ever reported was obtained by Miles from 

 a Kentucky Jersey breeder. Jersey 

 cows, pastured near some horses branded 

 on the left shoulder with the letters 

 U. S., produced calves with the letters 

 IT. S. in white hairs on the left shoulder. 

 Even the second generation is said to 

 have shown the same marks! In fact 

 some of the related examples of supposed 

 prenatal influence are so ridiculous as 

 to suggest that they were originally told 

 merely as jokes. At any rate there is 

 no evidence to support the theory that 

 malformation or peculiar marks can be 

 impressed on the offspring through the 

 medium of the imagination of the dam. 



Determination of sex — The dairyman 

 desires heifer calves, the beef raiser bull 

 calves, the dog raiser male pups, etc. 

 The possibility of predetermining the 

 sex of offspring has always been an al- 

 luring subject. Almost every imagin- 

 able scheme has been tested in deter- 

 mining sex in the human race and in 

 farm animals. The subject has at- 

 tracted so much attention that it 

 seems necessary to state, as briefly as 

 may be, the most important theories 

 which have been proposed. At first it 

 was supposed that one ovary and testis 

 (the right) produced only male offspring 

 and the other only female. This, how- 

 ever, has been proved not to be the case 

 as tested in man and swine. Thury 

 proposed the theory that eggs fertilized 

 as soon as mature produce females while 

 males result if fertilization is somewhat 

 delayed. Miles states that in Michigan 

 in ewes and cows served as soon as they 

 were in heat the female offspring were 

 twice as numerous as male in some 

 years while in other years the reverse 



was true. On most farms the male ani- 

 mals are allowed to run with the females 

 for a considerable period and presumably 

 the females are impregnated as soon as 

 in heat. Nevertheless the proportion of 

 male and female offspring is about equal 

 and this is unfavorable to the theory of 

 Thury. Moreover, the actual union of 

 the spermatozoon with the egg may not 

 take place for two weeks after service, 

 in fact it is utterly impossible to say 

 when it occurs. The union of the male 

 and female germ cells may take place 

 more promptly at the end than at the 

 beginning of the period of heat. 



Eelative age of parents — It' has been 

 claimed by Hofacker and Sadler that 

 female offspring predominate when the 

 sire is younger than the dam and male 

 when the sire is the older. The results 

 thus far obtained in testing this theory 

 are by no means uniform and do not 

 prove the point of contention. In the 

 case of man there are about 106 boys 

 born to every 100 girls without regard 

 to the relative age of the parents. 

 Martegoute states that the larger ewes 

 are more likely to bear female lambs, 

 but this is not in accordance with practi- 

 cal experience. Tegetmeier collected 

 statistics on the sex of colts from rac- 

 ing mares during a period of 21 years. 

 The total number of colts was 25,560, of 

 which 12,797 were female and 12,763 

 male. The males are in excess at birth 

 in many species of animals, as well as in 

 man, but there is a higher mortality 

 among males in early life so that the in- 

 equality may disappear or the females 

 may ultimately predominate. 



Some evidence has been accumulated 

 to show that as a result of oppressive 

 heat, overwork, defective nutrition or 

 the prevalence of disease the excess of 

 male offspring may be reduced. Baker 

 claims that "causes tending to increase 

 the birth rate tend also to increase the 

 proportion of female offspring." It does 

 not appear, however, that there is a pre- 

 ponderance of female offspring in races 

 of animals of unusual fecundity. 



Influence of sire and dam — It has 

 sometimes been assumed that the dam 

 exercises a greater influence than the 

 sire in determining the sex of the 

 progeny. Statistics adduced in support 

 of this assumption are not conclu- 

 sive. Wright maintains that " if a vig- 

 orous cockerel is mated with not more 

 than three adult hens, the cocks almost 

 always largely predominate in at least 

 the early broods; later this becomes un- 



