INHERITANCE IN ORGANISMS 



557 



and might appear either black or red, depending upon which showed 

 itself. The one which appeared would be a phenotypic character. 



597. Mendel. — The first scientific explanation of the manner in which 

 inherited characters are passed on was given by Gregor Johann Mendel 

 (Fig. 383), an Austrian peasant boy who became a monk and abbot in 

 the monastery at Briinn and who lived from 1822 to 1884. In the mon- 

 astery garden he experimented with the inheritance of characters in 

 garden peas and formulated laws of inheritance which have come to be 

 known by the term mendelism. He pubhshed the results of his work in 



Fig. 383.— Gregor Johann Mendel, 1S22-1884. {From Shull, 'Principles of Animal 

 Biology," after Report of the Royal Horticultural Society Conference on Genetics, 1906, and 

 by the courtesy of McGraw-Hill Book Company, Inc.) 



1866, but, owing to the fact that his contribution was in an obscure 

 pubhcation and that men's minds were occupied at the time with the 

 subject of evolution and the work of Darwin, which had appeared seven 

 years before, Mendel's contribution remained unknown to scientists until 

 the beginning of the present century. Mendel's work was done before 

 chromosomes were discovered, but all that has been learned since has 

 served only to justify his conclusions. 



598. Mendelism. — Mendelism involves particularly three principles 

 or laws which may be stated as follows: 



1. There is in each individual a pair of hereditary units corresponding 

 to each character which the individual possesses (law of paired units). 

 These we now know as genes, one coming from each parent. 



