LESSONS FROM NATURE. [Ciui . VIII. 



outer digits (toes) become more or less connected by skin, 

 as is also tho case with the corresponding digits of the 

 pigeon s hand. 



As regards pathology, Sir James Paget has declared, 

 Kromi.au.- spoukiiig &amp;lt;&amp;gt;f symmetrical diseases, that &quot;a certain 

 morbid change of structure on one side of tho 

 body is repeated in the exactly corresponding part of the 

 opposite side&quot; i.e., we have a spontaneous manifestation 

 of lateral homology. In the pelvis of a certain lion affected 

 with a kind of rheumatism Sir James remarked a deposit 

 which had formed a pattern more complex and irregular 

 than tho spots upon a map, while not one spot or lino on 

 one side failed to be represented with daguerreotype ex 

 actness on the other. He also considers that parts which 

 are serially, as well as those which are laterally homologous, 

 are likely to bo alToeted in a similar manner. Such serially 

 homologous parts are the back of the hand and the corre 

 sponding surface of tho foot, and those are likely to be both 

 modified in tho same manner, as also are the palms and 

 soles, the elbows and knees, together with the other serially 

 corresponding parts of the arms and legs. 



What explanation can be offered of these phenomena i 

 To say that they exhibit a &quot; nutritional relation,&quot; brought 

 about by a &quot; balancing of forces,&quot; is but a statement of the 

 fact, and affords no explanation of it whatever. Tho changes 

 are, of course, brought about by a * nutritional &quot; process, and 

 the symmetry is undoubtedly tho result of a &quot; balance of 

 forces ;&quot; but to say so is to allirm a truism. The question 

 is, what is the cause of this &quot;nutritional balancing?&quot; It 

 seems impossible not to concede tho existence of an internal 

 force. If this power be referred, as it seems Mr. Spencer 

 would refer it, to certain physiological units of which he 

 imagines each organism to be composed, there must none 

 tho loss bo recognised an innate power possessed by such 

 units of inheriting tho elVects of ancestral modification. 

 It is not easy to see the advantage of Mr. Spencer s reference. 

 It seems easier, simpler, and more consonant with known 



