172 POPULAR SCIENCE MONTHLY 



However, putting aside the extraordinary scientific interest of such 

 discoveries, and their bearing, ultimately, on the whole fabric of 

 human thoughts; you will see readily enough that if a rust fungus can 

 be transferred to a previously immune host through an intermediate 

 form the planting of such a form in a certain region might be the 

 cause of the ruin of a whole crop of wheat, oats, barley, or what not. 

 Agriculturists have long sought, and thanks more especially to the 

 knowledge derived from Mendel's researches, are learning how to 

 isolate rust-proof types of cereals. In this way the pest may be over- 

 come, but the vantage gained may again be lost in ways which would 

 never be suspected, and could not be prevented, but for Dr. Arthur's 

 illuminating researches. 



Mr. W. L. Tower, of the University of Chicago, has been for many 

 years conducting breeding experiments among beetles, choosing for 

 that purpose the Colorado potato beetle and its immediate allies. Only 

 the first part of his results has been published, but it is enough to 

 show that he has found out some exceedingly interesting and important 

 things and thrown new light on other matters not entirely new. For 

 example, in breeding the beetles, he found that through a number of 

 generations, the selection of extreme individuals (say dark, or light) 

 for breeding did not sensibly modify the race. But by a process of 

 very elaborate and careful breeding from isolated beetles, he discovered 

 that sometimes a character was inherited fully, sometimes not to any 

 appreciable degree, that is to say, it was possible to have two parents, 

 AA and AB, looking exactly alike, but the first having, the second 

 lacking, the property of producing offspring all closely similar to itself. 

 The importance of such facts from an economic standpoint are hardly 

 to be overestimated. Through such researches as those of Tower and 

 Mendel, we are coming to understand why it is so difficult to improve 

 a race by merely choosing those individuals which superficially appear 

 to be of a desirable kind. It is necessary to isolate them, and test 

 their properties through the character of their offspring, in order to 

 separate pure races. 



I have chosen only a few striking cases, and have said nothing 

 about the infant ideas of our own vicinity. At some future time it 

 may seem worth while to get up a local baby-show ; the more so because, 

 I regret to say, many of the infants known to me are lacking nurses, 

 and I do not know of any hospitable door steps on which to leave them. 



Ideas are not merely born once, but they suffer new births in the 

 minds of many persons. In truth, they are not precisely repeated, but 

 in each reincarnation are a little modified or augmented, so that the 

 thought of every person about a given subject has its own individuality. 

 This, however, presupposes that the child is alive, and not still-born. 

 If it has any vitality, it will call attention to that fact by metaphorical 



