380 KANSAS UNIVERSITY SCIENCE BULLETIN. 



groups of cells fail to separate and thus produce spermatids 

 with two or four tails and as many simplex groups of chromo^ 

 somes; minor abei'rations occur throughout all stages. Can 

 these be held to prove that there is no constancy in the processes 

 and results of spermatogenesis? Can deviations from the 

 normal or average be regarded as an argument against a type? 

 If so there can be no general laws in biology. 



