488 NATURAL SCIENCE. s^^.. 



No doubt there is much truth in all these considerations, and it 

 is well that a Naturalist who can speak with authority should occa- 

 sionally challenge the dogmas that are prone otherwise, by frequent 

 repetition, to gain currency as well-ascertained facts. With regard 

 to the age of the earth in terms of years, we are bound to admit that 

 the solution of the problem is almost as far off as ever ; and if a solu- 

 tion should eventually be found, we are convinced that the Astronomer, 

 and not the Geologist or Biologist, will have the satisfaction of its 

 discovery. 



The Study of Variations in Animals. 



Serious warnings that our philosophy may be attempting to 

 advance too rapidly are not only conspicuous in the latest discussions 

 of such wide problems as those to which we have just alluded. 

 Recent literature contains many new facts that are likely to revolu- 

 tionise current views on several of the minor questions of organic 

 evolution ; and if Mr. W. Bateson's researches on the variation of 

 multiple parts in animals prove to yield something more than a 

 phantom as a result, Biologists must cease to believe in some of their 

 most fundamental tenets. It may be a satisfaction to learn that the 

 five-fingered limb of a lung-breather is not a direct modification of 

 the primitive fin of a gill-breather, but has merely arisen by the 

 independent segmentation of the same kind of tissue that gave rise 

 to the fins. It may also be a satisfaction to the student of teeth in 

 the mammalia to know that the various modifications really cannot 

 be regarded as all derived from one fundamental fixed type. It is 

 somewhat startHng, however, to read Mr. Bateson's preHminary 

 announcement of his conclusions {Proc. Zool. Soc, 1892, p. 114), which 

 are shortly to be elaborated in a special treatise, and the following 

 paragraph is especially noteworthy : — 



" The received view of homology supposes that a varying form 

 is derived from the normal much as a man might make a wax model 

 of the variety from a wax model of the type, by small additions to, 

 and subtractions from, the several parts. This may, to our imagina- 

 tions, seem perhaps the readiest way by which to make the varying 

 form if we were asked to do it ; but the natural process differs in one 

 great essential from this. For in nature the body of the varying 

 form has never been the body of its parent and is not formed by a 

 plastic operation from it ; but in each case the body of the offspring 

 is made again from the beginning, just as if the wax model had gone 

 back into the melting pot before the new model was begun." 



Our present methods of Comparative Anatomy, according to 

 Mr. Bateson, " though they are ingenious, logical, and orderly, are 

 orderly because they are made without regard to the ways of 

 Variation, which is arbitrary and capricious and follows no order 

 that we have yet devised." 



