GENERATION OF ANIMALS, V. vii. 



This is the way in which the testes are attached to 

 the seminal passages, which in their turn are attached 

 to the blood-vessel which has its starting-point at the 

 heart near the part which sets the voice in movement." 

 And so, as the seminal passages undergo a change at 

 the approach of the age when they can secrete semen, 

 this part undergoes a simultaneous change. And as 

 this changes, so too does the voice — to a greater 

 extent in males, but the same happens with females 

 as well, though the change there is less obvious ; and 

 one result of this is that, as we say, the voice " is 

 breaking " ^ during the time that it is uneven. After 

 that, it settles down into the deep or high pitch 

 belonging to the age of Hfe which is to succeed. If 

 the testes are removed, the tautness of the passages 

 is slackened, just as when the weight is removed from 

 the cord or from the warp ; and as this slackens, the 

 source (or principle) which sets the voice in movement 

 is correspondingly loosened. This then is the cause 

 on account of which castrated animals change over 

 to the female condition both as regards the voice and 

 the rest of their form : it is because the principle from 

 which the tautness of the body is derived is slackened. 

 The reason is not, as some people suppose, that the 

 testes themselves are a ganglion of many principles. 

 No ; small alterations are the causes of big ones, not 

 in \'irtue of themselves, but when it happens that a 

 principle changes at the sarne time.'' The principles, 

 though small in size, are great in power : that is what 

 it means to be a principle — something which is itself 

 a cause of many things, while there is nothing more 

 ultimate which is the cause of it. 



* Lit., " ' bleating like a goat ' as some people call it." 

 " Cf. 716 b 3, etc 



551 



