No. 547] ALTEEXATIVE J XII Ell IT A X( E IX IIOS 



435 



Immunity to the Texas Cattle Ticks 

 I am able fully to confirm Mr. Borden's statements 

 (loc. cit.) that the pure Brahma cattle and the hybrids 

 are perfectly immune to the Texas cattle tick. Fig. 8 

 shows the ordinary conditions of the native Durham or 

 Hereford cattle, while Figs. 9, 1 and 3 show the condi- 



tions of the pure Brahma and hybrids all running 

 together on the same range. I was not able to ascertain 

 definitely the inheritance behavior of this character (im- 

 munity to ticks) in the F 2 progeny. However, it is ex- 

 pected that data on this point will be available in the 



The statement by Mr. Borden (loc. cit.) that the 

 hybrids running on the range average about 50 per cent. 



