HEREDITY AND RADIUM AT DUBLIN 185 



Harmer, President of the section. He put the law in the fore- 

 front of his address, and made some hopeful suggestions. 



The present century (he said) has seen a remarkable develop- 

 ment of the study of the problems of heredity and variation, 

 largely as the result of the interest awakened in the resuscitation 

 of Mendel's experimental work from the oblivion in which it had 

 remained for so many years, though the general problem is 

 being attacked concurrently by investigators who attach more 

 importance to the statistical method of study. Professor 

 Bateson has given the name " Genetics " to the experimental 

 study of heredity. Some of the more recent conclusions of 

 the workers in Genetics are to be discussed by this Section 

 during the present meeting. It cannot be doubted that an 

 accurate knowledge of the principles of heredity is destined to 

 exert a marked influence on the practical concerns of humanity. 



That was a sonorous generality appropriate to a Presidential 

 address, but Mr. Harmer had in his mind a precise application 

 of the law to his particular subject. He has been studying the 

 protozoa, and been much struck with the many unsolved problems 

 and difficulties connected with the variations of certain remark- 

 able appendages known as " avicularia." He found what he calls 

 vicarous or adventitious avicularia of a highly specialised 

 description associated in one and the same family with the 

 normal type of avicularium, and could not account for their 

 presence, but made this suggestion — very remarkable as coming 

 from a precise zoologist deeply absorbed in a particular 

 inquiry : 



It appears to me worth while to suggest that some of our 

 difficulties might be removed by appealing to the results 

 obtained by workers on Mendelian inheritance. An essential 

 part of the theory here involved is .that in the formation of the 

 gametes of an organism there is a segregation of certain paired 

 or " allelomorphic " characters whereby some of the gametes are 

 endowed with qualities by virtue of which they transmit one of 

 the characters, while the rest of the gametes become capable 

 of transmitting the characters of the other member of the 

 allelomorphic pair. It has recently been made probable by 

 Professor Bateson, whose views have been confirmed by others, 

 that the actual appearance of a particular character may be 

 dependent on a coupling of two allelomorphs belonging to 

 distinct pairs. If only one of them is present the character will 

 not show itself. The phenomenon of reversion on crossing is 

 thus explained as due to the combination of allelomorphs 

 present in the isolated condition in two parental forms. 



