ABC 



ABC 



abC 



abC 



aBC 



aBC 



ABC 



ABc 



ABC 



aBC 



Fig. 8. — Types of haploid spore produced by meicsis in an F^ hybrid between two 

 species of the green alga Chlamydomonas. Top: the two spore types of the parents 

 have segregated, i.e. Large (A), Thick-walled (B) and Loose-chloroplast (C) from 

 Small (a). Thin-walled (b) and Adhercnt-chloroplast (c). A'liddle Row: two of the 

 results where separation is reductional at the first division for all the three genes 

 and in consequence only two different types are formed. This event ensues whenever 

 there is no chiasma between any of the genes and the centromeres of the chromo- 

 somes that are carrying them. N.B. on the left, recombination is of C-c with A-a 

 and D-b; on the right, o( A~a with B-b and C-c. Bottom Row: two of the results 

 where separation is cquational at the first division for at least one of tlie three genes 

 and in consequence four different types are formed. This event ensues when a chiasma 

 has been formed between the gene in question and the centromere of its chromosome. 

 N.B. in each case the four types include the parental combinations, but they can all 

 be recombinants (with kind permission, after Mocwus, 1940, and unpublished). 



