12 3 4 



A ^"^ A ^^ • Single set: Haploid 



B J^ A ^^ \ Double set : Chromosomes in Pairs : Diploid 



C •—• /\ /% • Chromosomes in Threes: Triploid 



A ^^ 



O 2S A y^ ; Chromosomes in Fours: Tetraploid 



£ "J" ^|* ^^ • One Pair Lacks a Chromosome 



A 



p ?^" A ^^^ , First Pair with an Additional Chromosome: 

 — A ^^ • Trisomic 



^^ ^ Second Pair with an Additional Chromo- 



" ^~" /\ ^^^ • some: Trisomic 



^_ ^ ^^ J Second and Fourth Pairs Each with an 

 ti mmma /\ ^\^ • Additional Chromosome: Double Trisomic 



A 



Figure. 66. Diagrams to show some of the different groups of chro- 

 mosomes that produce diverse types of organisms. The basic number 

 of chromosomes is taken as four. A, chromosomes not in pairs, the 

 haploid condition, found in germ cells and in some organisms. B, 

 chromosomes in pairs, the diploid condition found in most organ- 

 isms. C to F show other conditions known to occur. 



323 



