THE EVIDENCE OF EVOLUTION. 393 



evolution is concerned. Now, if they can not be explained hj the 

 slow and gradual -accumulation of individual variations, evidently 

 the second alternative of Darwin's oniiiniil pro^^osition remains. 

 This was based on the sports, on those rare and sudden changes which 

 from time to time are seen to occur among cultivated plants, and 

 which in these cases give rise to new strains. If such strains can be 

 proved to offer a better analogy to real systematic sjjecies, and if the 

 sudden changes can be shown to occur in nature as well as they are 

 known to occur in the cultivated condition, then in truth Darwinism 

 can a fiord to lose the individual variations as a l)asis. Then there 

 will be two vast dominions of variability, sharply limited and 

 sharply contrasted with one another. One of them will be ruled by 

 Quetelet's law of probability and by the unav()i(hd)le and continuous 

 occurrence of reversions. It will reign supreme in the sciences of 

 anthropology and sociology. Outside of these, the other will become 

 a new domain of investigation, and will ask to be designated by a new 

 name. Fortunately, however, a real new designation is not required, 

 since previous to Darwin's writings the same questions were largely 

 discussed and since in these discussions a distinct name for the sud- 

 den and accidental changes of species into one another was regularly 

 used. At that time they were called '^ nnitations," aiid the phenome- 

 ]ion of nnitability was more or less clearly distinguished from that of 

 variability in a more limited sense. Especially in France a serious 

 scientific conflict raged on this point about the middle of the last 

 century, and its near relation to religious (fuestions secured it a large 

 interest. Jordan and Godron were the leaders, and numerous dis- 

 tinguished botanists and zoologists enrolled themselves under their 

 banners. They cleared part of the way for Darwin and collected a 

 large amount of valuable evidence. Their facts pleaded for the 

 sharp and abrupt delimitation of their species, and asked for another 

 explanation than that which was derived from the ordinary, slow, 

 and continuous variations. 



Their evidence, however, Avas not complete enough to command the 

 decision in their behalf. The direct proof of tlie sudden changes 

 <jou]d not be offered by them, and they allowed themselves to be 

 dri\'en to the acceptance of supernatural causes on this account. 

 Thereb3^ however, they lost their influence upon the progress of 

 science, and soon fell into oblivion. 



Instead of following this historical line, however, I have now to 

 point out one of the weightiest objections against the conception of 

 the origin of species by means of slow and gradual changes. It is 

 an objection which has been l)rought forward against Darwin from 

 the very beginning, which has never relented, and v^hich often has 

 threatened to impair the whole theory of descent. It is the incompat- 

 ibility of the results concerning the age of life on this earth, as pro- 



