10 



Genetic Studies i7i Rahhits 



of growth of three F^^ animals from the Flemish-Polish cross (cf. Table V, 

 p. 25). In the large breed to which our experience has been limited^ 

 the Flemish, growth is relatively slower and the curve is consequently- 

 more drawn out. In the case of the four animals whose growth is shewn 

 on Fig. 7 the maximum weight, prior to cessation of growth, was not 

 attained until an age of 14-15 months was reached, and it was also 

 noticed that these animals were very slow in arriving at sexual maturity. 

 Nevertheless the usual decline in weight subsequently set in, and in 

 this respect the heavier breed conforms to the type of the curve exhibited 

 by the lighter animals of Fig. 6. It would be of interest to learn 

 whether a rise in weight occurs later in life, but owing to lack of space 

 we have been unable to keep the animals long enough to test this point. 

 It will be noticed from Figs. 6 and 7 that at seven months the F^ animals 



Weight 

 in lbs. 



7- 



6- 



Agein • T" 



months! 8 



1 — r 



9 10 



~i r 



11 12 



n 1 1 1 1 1 



13 14 15 16 17 18 



Fig. 7. Growth curves for 4 Flemish rab.bits. (Cf. Table I, p. 21.) 



were markedly heavier than the Flemish. Their early growth was 

 much more rapid and their sexual maturity much earlier. The Flemish 

 animals which provided the data for Fig. 7 had been inbred for several 

 generations (cf Fig. 12, p. 20), and it is not impossible that inbreeding 

 may be connected with slow growth and delayed sexual maturity. Early 

 maturity is not necessarily connected with small size as is shewn 



