i893- NOTES AND COMMENTS. 163 



in the evolution of part of a vertebrate skeleton is thus to be explained 

 on purely mechanical principles. 



To the discussion of this subject another interesting contribution 

 has just been made by Professor Cope, who describes two cases of a 

 repaired elbow-joint, one in a man the other in a horse [Proc. Amer. 

 Phil. Soc, vol. XXX., pp. 285-290, pi. ix.). In his \vell-kno^\•n work 

 on " Animal Mechanism," Marey has already described instances of 

 the natural healing and repair of diseased or dislocated joints — how 

 a new articulation is often completely formed, not only with accu- 

 rately fitting faces, but also provided with the requisite ligaments 

 and synovial fluid. Professor Cope's paper thus deals merely with 

 the details of two remarkable examples of this repair, in which a new 

 elbow-joint was completely formed after a dislocation. As the author 

 remarks, if the mechanical necessities of a case of this kind lead to 

 the production of a completely new and finished joint within the 

 space of a few months, " how much more easy has it been for stimuli 

 of allied character to develop the features of normal articulations 

 during the ages of geologic time." 



" We have here, also," says Professor Cope, " an instructive 

 lesson as to the matter of inheritance. Everyone knows that mutila- 

 tions, luxations, &c., are not usually inherited. This is because they 

 are not ' acquired,' in the proper sense of the word. Since characters, 

 truly acquired, are inherited, it is evident that a long continuance of 

 the stimulating cause is necessary to produce a true acquisition. 

 The difference between a character produced by causes apart from 

 the normal life of an animal, and not repeated, and those produced 

 by causes operating daily and hourly for geologic ages, is necessarily 

 very great." 



A Glimpse of the Tropics. 



In the recent December and January numbers of the Botanical 

 Gazette, Mr. D. H. Campbell gives an account of a six weeks' vacation 

 spent last summer in the Hawaiian Islands. In position, these islands 

 are unique, being "more isolated than any other land of equal area 

 upon the globe." They are 2,350 miles from the nearest part of the 

 American mainland, the bay of San Francisco, and about the same 

 distance from the Marquesas and Samoa Islands to the south, and 

 the Aleutian Islands a little west of north. As Wallace remarks in 

 his Island Life, they are "wonderfully isolated in mid-ocean," the 

 nearest of the widely-scattered coral reefs and atolls being six or 

 seven hundred miles distant, and all nearly destitute of animal or 

 plant life. 



The group consists of seven large inhabited islands and a few 

 rocky islets, extending in a S.E. direction just within the tropic of 

 Cancer. Hawaii, by far the largest and most southerly, is 70 miles 

 across and about the size and shape of Devonshire ; the greater part 



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