Heredity and Sex 



MENDELISM AND SOME OF ITS RECENT DEVELOPMENTS 

 Bv FRANK E. LUTZ. 



THE history of science is as full of 

 episodes replete with " human 

 interest" as is the history of 

 nations. Not the least of these is the 

 story of Gregor Mendel, a peasant, 

 later a monk, and finally Abbot at Briinn, 

 but now known not for his theology or 

 his kindly deeds to his fellows, but for 

 his patient and successfid work in his 

 avocation — the study of heredity. The 

 principal material which he used in this 

 study was the common pea, and his 

 results were published in an obscure 

 journal in 1865. Darwin knew of his 

 work but failed to appreciate its signi- 

 ficance. In fact, it remained unnoticed 

 \mtil eighteen years after Mendel had 

 died when, independently but simul- 

 taneously, it was 

 brought to our at- 

 tention, together 

 with important 

 confirmations, by 

 three noted bota- 

 nists: De Vries, 

 ("orrens, and Tsch- 

 ermak. Its redis- 

 covery has not 

 only given us a 

 theory of heredity 

 which has revolu- 

 tionized the practi- 

 cal breeding of 

 plants and lower 

 animals, but also 

 it has given a new 

 impetus to the ex- 

 perimental study 

 of evolution and, 



through the " eu- < -regor Mendd. Al.lx.l of 



,, in plant hybridization (1853 



geniCS movement, tion of important principles 



l)ids fair to play an important part in 

 the development of human society. It 

 is fitting, therefore, that the American 

 Museum should arrange exhibits illus- 

 trating the principles of Mendelism. 

 In the Darwin hall of the American 

 IVIuseum, featiuTS of the Mendelian 

 law of heredity are shown by means 

 of peas and rats, while in the insect 

 hall not only Mendelism, but also the 

 later developments of Mendelism — 

 its relation to the mechanism of the 

 germ cell and to sex — are illustrated. 



As an illustration of Mendelism in its 

 simplest form we may take the following : 

 The commoner of the two beetles — 

 both undesirable immigrants from Eu- 

 rope — which feed upon our asparagus 

 is Crioccris aspar- 

 agi. It is a small 

 gi-een creature 



with cream-colored 

 markings. In some 

 individuals these 

 markings consist 

 of three small spots 

 on each wing cov- 

 er; in others these 

 spots are larger, 

 and the two front 

 ones on each side 

 are joined. Now, 

 if an asparagus 

 beetle having the 

 spots small and 

 separate mates 



with one having 

 the spots large and 

 joined, the off- 

 spring (the " hy- 

 brids" or, as this 



229 



Uriinn. whose experiments 

 -1884) led to the formula- 

 of heredity 



