FREE INSTITUTE OF SCIENCE 



51 



MENDEL AND HIS LAW 



any other. Second, on crossing individuals that differed in a pair of unit char- 

 acters, the first hybrid generation will show only the dominant member of the 

 pair. The next generation will furnish three dominant, one of which is pure 

 and the other two hybrid, while there will be only one recessive. 



At this time little was intimately known of the nature of the reproductive 

 process in plants and animals, but there was enough in what Mendel had done 

 to make him feel that in the fertilizing cells, in ovule and pollen, must lie the 

 secret of the behavior of the individuals which spring from them. 



Fourteen years later another paper of Mendel's, in the same obscure 

 journal, tried to solve some difficulties that appeared when St. John's wort 

 plants were crossed, but these hybrids are so complicated that Mendel's second 

 paper lacks the clearness and convincing character of his first masterly compo- 

 sition. 



Mendel's law is so entirely the result of painstaking observation that there 

 is no possible question as to its truth concerning a very large number of animal 

 traits. But while it is perfectly clear that the facts are as Mendel states them, 

 there was nothing in his researches to indicate why they are true. He made a 

 few surmises, which in some respects were rather happy guesses, but concerning 

 which neither he nor any one else at the time could have any real certainty. 



Not until Weismann made his famous researches was it possible to see any 

 structural reason in the egg itself why Mendel's law should be true. Now it is 

 not hard to see that we are very much closer at least to a structural explana- 

 tion of the facts expressed in Mendel's law. 



There are various avenues by which the scientist has reached his develop- 

 ment. Some of our greatest biologists are the product of travel. Darwin's 

 voyage on the ''Beagle" was undoubtedly the determining factor in his life. 

 Alfred Russell Wallace did all his best work traveHng in South America or in 

 the Malay region. Mendel and De Vries did their great work in the garden. 

 Careful planting and watching and recording made the basis of their training. 

 As a science grows more compHcated, as its general truths become well known 

 and investigation becomes the work of the specialist, the laboratory student 

 comes to the front. It was training such as this that gave to the scientific 

 world the thoughtful, painstaking scholarship of August Weismann. This 

 patient worker was born in 1834 at Frankfort-on-the-Main. His Hfe is singu- 

 larly free from all the ordinary chances and mischances which make up the 

 biography of most men whose lives attract attention. Weismann's career is 



