244 POPULAR SCIENCE MONTHLY. 



quicker than light, but that is all, and the one who unravels the mys- 

 tery will deserve to rank with the greatest of discoverers. 



In like degree are we ignorant of electrical and magnetic phe- 

 nomena which depend upon the ether. When the ether is understood 

 we shall be able to understand in a mechanical sense how moving a 

 magnet disturbs every other magnet wherever it may be, why chemical 

 compounds are possible, why crystals assume geometric forms, and why 

 cellular structure in plants and animals can embody what we call 

 life. To discover the nature and mode of operation of this ether is 

 the work of the twentieth century, and we may be sure that he who 

 accomplishes this will deserve to rank with the highest; indeed it may 

 fairly be said that in importance it is not secondary to anything known, 

 for it is apparently concerned in all phenomena from atoms to masses 

 as big as the sun. 



The biologists have great problems on hand for solution. The nine- 

 teenth century work made it clear that all the forms of vegetable and 

 animal life of to-day are the product of slow changes in form and 

 functions of living things reaching back millions of years. The suc- 

 cessions of some forms were well worked out and the principle estab- 

 lished. We call it evolution and everybody nearly believes that this 

 represents the truth in the matter, but how these changes occur and 

 what necessitates them remain as mysterious as ever. Darwin spoke 

 of natural selection. There were all sorts of variations in progeny, and 

 the ones best fitted to the environments survived, but he gave no reason 

 why there should be variations, and this is the great question to-day. 

 Many are at work to discover this, and some who have worked in this 

 line have stumbled upon some very unsuspected facts. There has 

 been assumed that like would produce like, and that heredity could 

 and would account for abnormal structures when parents for any rea- 

 son through new environment had acquired new habits or new struc- 

 tures of any kind. Now it has been shown that such changes of struc- 

 ture or of habit seldom if ever appear in the progeny. For instance, 

 no matter how many generations of mice have their tails cut off each 

 new mouse has the same old length of tail. Each lamb has as many 

 tail vertebrae as did those of hundreds of years ago, though all lambs 

 have their tails cut off when young. Such acquired character is not 

 inherited. Nature pays no attention to any changes save such as she 

 herself initiates, and the conditions she herself adopts remain to be 

 found out. Sometimes she makes monsters and sometimes geniuses, 

 but never by external environment, always de novo. This throws 

 overboard the principle good and thoughtful men have so long 

 cherished, that the good habits of one generation would be a hereditary 

 possession of the next. The conditions for heredity are now a most 

 absorbing study among some of the foremost biologists. It is sug- 

 gestive that at this late day such a reversal of opinion on this ques- 



