1 36 TJ^ANSMISSION OF ACQUIRED CHARACTERS 



between body and germinal matter, apart from which the 

 concept of modifications is of no value. In artificial culture 

 the whole character of the unicellular organism — its particular 

 metabolism — is altered ; it multiplies by dividing into two or 

 more parts, which naturally retain the altered constitution. 

 But this is worlds away from the supposed case of an alteration 

 in the structure of the little toe so affecting the germ-cells that 

 the offspring inherit .a corresponding deformation.* 



Prof. Adami (1901, p. 13 19) says: "By subjecting a growth 

 of pigment-producing bacteria to the action of a temperature just 

 below that which will cause their death, we can bring about a 

 loss of pigment production, so that the rapidly-succeeding genera- 

 tions are perfectly colourless ; but gradually, in the course of time, 

 the cultures made from the original (heated) tube regain the power 

 of pigment production. This may be in two or three days, or, again, 

 only after several transplantations at the end of two or three 

 weeks ; and when we remember that a bacillus divides and so forms 

 a new generation in, on the average, something considerably less 

 than an hour, it is seen that the acquired character may be impressed 

 upon a race for some hundreds of generations. The more intense 

 the alteration to which the bacillus is subjected, the longer and the 

 more frequently the race is subjected to the altered temperature 

 conditions, the longer it is before there is a sign of return to the 

 normal." 



These are interesting and reliable facts, but their citation as 

 evidence of the inheritance of " acquired characters " is misleading, 

 since no bacilli show any hint of the distinction between somatic 

 and germinal material on which the definition of " acquired char- 

 acters " depends, nor do they multiply except by division and 



* It is surprising that even Prof. Oscar Hertwig (1898) supports his 

 argument in favour of the transmissibiUty of somatic modifications by 

 citing cases of inheritance in unicellular organisms. We are told that 

 the irritability of certain Algae to light may be modified by exposure to 

 strong light and to high temperature, and that " nobody would be sur- 

 prised " if the progeny also showed " some similar property." But this 

 is hardly evidence of the transmission of a modification ! We are also 

 told that under artificial conditions some bacteria may lose their toxic 

 properties, and may transmit this somewhat negative character of lost 

 virulence. This is admitted by all, but it is an ignoratio elenchi. 



