90 Missouri Agricultural Report. 



crossed with standard sorts the hybrid grows even taller than the 

 standard parent. 



These illustrations are sufficient to make clear the law of 

 dominance and the fact that this law is not universal. We come 

 now to a more important law, the law of separation of character 

 pairs. It is this law that is ordinarily meant when we speak of 

 Mendel's law, because it is so much more important than the law 

 of dominance. 



It is part of the irony of fate that Mendel's discoveries were 

 utterly ignored and even forgotten during his life time. He never 

 knew he had made an epoch making discovery. When the whole 

 world went to breeding improved varieties of plants these dis- 

 coveries were made again. Now we are building a monument to 

 Gregor Mendel at Briinn, Austria, in the little monastery garden 

 in which his epoch making work was done. 



MENDEL'S LAW OF SEGREGATION. 



We have seen what happens when a pair of antagonistic 

 characters are brought together ; that is, what happens during the 

 life of the individual bearing these two characters. But what 

 happens to this character pair in passing to the next generation? 

 The bodies of all plants and animals are composed of small parts 

 called cells; each of these cells is, in a sense, an elementary plant 

 or animal. Our bodies are in reality colonies of very minute 

 organisms, each of which has its particular work to do. Some of 

 these cells manufacture the digestive juices, some form the bone, 

 others become muscular tissues; some of them become red blood 

 corpuscles, etc. While growth is still in progress it is these cells 

 that do all the growing. When one of them reaches full size, it 

 splits into two, and each of the new cells thus formed in turn 

 grows to full size. The internal structure of the cells is very 

 complex. Indeed, it is a wonderful structure, but I can not here 

 stop to describe what we know about it. It would take more time 

 to do that than is available for this whole lecture. Prof. E. B. 

 Wilson has written a 500-page book about these cells, and what 

 has been learne,d since that book was written would make another 

 book as large. Suffice it to say that when one of these cells reaches 

 maturity, and splits into two new cells, each of the important 

 organs in the cell divides also, so that, speaking in a general way, 

 each of the new cells is provided with the same organs as the old 

 cell had. 



