Tht, Possible' Combinations PrcdtLctd by fertilisation in, an/ 

 Organism the Cells of \vhicfi Contain four Chromosomes. 



The Four Chromosomes 

 Pamirs Co [he Onnif. fes, 



are distributed- irv 

 wki&h, may therefo 



Contain: anu cf t/i&JclLowiny Combinations. 



10 II ID 



Wktn UrdUscUion, taJiet place., t*v@a.me tu fuse,. T/LefiUcu-csi-g CimLtna.titns 



an.J art proinJJc cmccrMny & the, Jrtyu.tncy tvMi uhicJiOuy ccciLnm the, diagram* 



I 1010 HI 





FIG. 1C. The diagram shows that in an organism the cells of which contain four 

 chromosomes, six different combinations of two chromosomes are equally pro- 

 bable in the gametes. It also shows that in fertilisation these pairs contained 

 in the gametes may be combined in thirty-six different ways. In six of these 

 the chromosomes are the same as in the parent organism. Thus in an organism, 

 the cells of which contain four chromosomes, there is one chance in six that the 

 original combination will be reproduced in the offspring, and this only when 

 it is assumed that the chromosomes in both parents are the same. In man, 

 where there are thirty-two chromosomes in a cell, the number of different sets 

 of sixteen is enormously large, and the chance of the original combination being 

 reproduced in fertilisation is only one in over six hundred million. 



