400 PROGRESS OF SCIENCE IN THE CENTURY. 



there is at first no such distinction. We inherit our- 

 selves: organism and inheritance are, to begin with, 

 one and the same. For by inheritance we simply 

 mean, in plain English, all that is involved in the 

 vital material which is set apart from parents to 

 start a new life. The inheritance is the fertilised 

 egg-cell, and heredity is no entity, but merely a 

 convenient term for the relation of genetic continu- 

 ity between successive generations. 



But our particular point is that " Heredity,'' like 

 '^ Horologity in clocks," like ^' Phlogiston " and 

 " Caloric," and how many more ^^ entities," has 

 yielded before the sharpness of William of Occam's 

 razor. 



(4) Another change is marked by the more criti- 

 cal attitude which is now taken up in regard to 

 various sets of facts or alleged facts relating to in- 

 heritance, which were once accepted without ques- 

 tion. We allude to the modern criticism of alleged 

 cases of maternal impressions, " telegony," and the 

 transmission of acquired characters. Experience 

 has brought home the lesson that easy-going accept- 

 ance of the first solution offered is not the scientific 

 method. The most important line of criticism is 

 that which has at least shaken the formerly wide- 

 spread belief in the transmission of acquired char- 

 acters or somatic modifications. The scepticism 

 which Kant and Prichard and others had long before 

 expressed was re-asserted more convincingly by 

 Weismann in 1883 in his thesis that the child in- 

 herits from the parent germ-cell, rather than from 

 the parent body. 



Methods. — The problems of heredity have long 

 since ceased to be studied in the arm-chair. They 

 have been attacked precisely and practically by 

 several distinct methods, of which the most im- 



