250 



MICHAEL F. GUYER. 



/I? 13/35 t<< It SIS 1*5 16 7.S 8 QS 9 9.S /O /OJ ,/ ,/s /t /ZS/J *3.f 



TEXT-FIG. 2. A, frequency distribution of head-lengths of 500 spermatozoa 

 from a Plymouth Rock fowl. 



Scale value ... 8 8.5 9 9.5 10 10.5 n 11.5 12 12.5 13 13.5 14 14.5 15 15.5 16 

 Frequency ...i i 5 42 206 151 83 6201100001 

 a, frequency distribution of head-lengths of 100 spermatozoa from the same 

 fowl in a different preparation and by a different observer. 



Scale value 9 9.5 10 10.5 n 11.5 



Frequency 3 2 37 31 25 2 



