22 THU BRADSHAW LECTUKK 



])irtli to twins falls into disgrace and is fatted and 

 killed for beef, because the farmer sells the milk 

 which is in excess of what is required for the 

 calf. Twin calves are therefore very rare. 

 Breeders also recognise the male influence, and 

 if many ewes throw single lambs as the result 

 of conception to a particular ram, that ram is 

 discarded. 



Dissimilar and Identical Twins. 



There are two forms of twins generally recog- 

 nised. In one there has been a simultaneous, or 

 nearly simultaneous, fertilisation of two ova, an 

 ovum descending probably from each ovary at 

 the same menstrual period. Such twins may 

 differ in sex, in height, in appearance and in dis- 

 position, presenting only the general resemblance 

 of brothers and sisters. The other form is 

 believed to result from the division of an ovum 

 after all the elements for development are complete. 

 These are invariably of the same sex and are 

 enclosed in the same membranes. In height, 

 appearance, and character they so closely resemble 

 each other as to be often spoken of as " identical " 

 twins. Shakespeare in "Twelfth Night" was 

 guilty of confusing the first form with the second, 

 when he founded the plot of his play on the 



