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been evolved through natural selection acting through long periods of 

 time from a few primitive and simple forms of life." 



It will be observed that Mr. Darwin does not attach much weight 

 ■to environment as a great agent or factor in the origin or modification 

 of species. Other naturalists of eminence differ from Mr. Darwin in 

 this respect, and maintain that the influence of snrrounding physical 

 conditions, as held by Lamarck, is quite as potent a factor as natural 

 selection, in bringing about the changes which are ever taking place in 

 the structure of organic life. It has often been observed that when 

 certain kinds of animals change their habitat, organs that cease to be 

 useful gradually disappear, while new organs or adaptations of already 

 existing ones to changed habitat as surely come about. In the January 

 number of the Popular Science Monthly there is published an article by 

 A. S. Packard, whom most of you have heard about, on the effect of 

 cave life on animals, in which he shows most conclusively that gradual 

 loss of the organs of sight occurs to animals so situated, and that modi- 

 fication of other organs takes place, such as the lengthening of the 

 antenna? or feelers, etc., — that is, the sense of touch becomes 

 greater as the necessities of the conditions demand its use. In such 

 cases as these Dr. Packard thinks there is little room for the operation 

 of natural selection, and that it plays a very subordinate part in the set 

 of causes inducing the origin of these forms. I will not attempt to 

 state the evidences which have been advanced by scientists to prove the 

 relationship and unity of organic life as manifested by embryology, by 

 rudimentary organs found in many animals for which now there is 

 apparently no use, and by the fossil remains of animals now extinct but 

 showing close affinity to those now living, but will only say in con- 

 clusion that the longer anatomical and geological investigations con- 

 tinue, the more surely does it appear that all animated beings began 

 their life course in the form ot a simple cell, and that by a long process 

 of evolution they have come to be differentiated into the numberless 

 forms in which we now find them, all tied together by an endless chain 

 without even one missing link. 



