GENETICS 149 



of biological relatedness. Such integrity of character is, 

 indeed, the truest safeguard of genuine friendship as 

 distinguished from transient forms of alliances of expediency, 

 miscalled '' friendships " (pseudo-symbiosis), which usually 

 end when the particular expedient purpose which they served 

 fails to manifest itself as it is also that of genuine symbio- 

 genesis. 



There is, as is well known, a constant danger of over- 

 specialisation (extreme specialisation, extreme determination) 

 in certain directions, and a proper cross one that receives its 

 legitimacy from adequate symbiotic factors is known to be of 

 good effects in neutralising at least some excesses and making 

 good some deficiencies, which shows that a cross signifies much 

 more in general qualitative and bio-dynamic effects than 

 Mendelism would lead us to suppose. We shall see more 

 evidence thereof later on, and we shall conclude all the more 

 certainly that knowledge of the causes and the degree of 

 friendship or antagonism relative and absolute obtaining 

 between genetic units or even biological substances, just as 

 between organisms themselves, is essential to proper, i.e., 

 discriminating genetics, requiring, as it does, a proper bio- 

 logical diagnosis. 



Making due allowance for the bio-dynamic effects of 

 adequate crossing, and for what is entailed in the previous 

 maturation of the uniting elements, we may say that such 

 crossing achieves nothing less than the transmutation of 

 organic currency, i.e., products for exchange in particular 

 that of the genetic and nutritive kinds, i.e., it presents a 

 genuine form of biological "alchemy" through symbio- 

 genesis. 



In order to understand the true significance and alchemy 

 of crossing, however, it must again be emphasised that it is 

 preceded by that other alchemy of nutritional "amphimixis " 

 on which I have repeatedly insisted. Indeed, the part played 

 in symbiogenesis by nutrition is so great that frequently, as is 

 well known, a nutritive stimulus is enough to start the all- 



