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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



still, it is well known that our familiar eft or 

 newt may lose half of its tail without suffering 

 any permanent loss ; a natural process of repara- 

 tion and growth in the starfish, in the crab and 

 lobster, and in the newt, in due time providing 

 new members for old ones. Man in one sense 

 may well envy the reparative powers of his in- 

 ferior neighbors ; since even in the comparatively 

 small matter of teeth he has to place himself 

 under the tender mercies of the dentist in event 

 of loss, and must view with hopeless gaze the 

 disappearance of the last joint of a finger or toe. 

 Although the physiologist is unable in the 

 present state of his science to explain the exact 

 and intimate manner in which the hydra and 

 other animals reproduce their tissues, we may 

 nevertheless, by a very homely simile, contrive to 

 gain a broad idea of the nature of these repara- 

 tive powers. We thus must firstly note that the 

 process is simply one of nutrition, or nutritive 

 growth carried out to a high degree of develop- 

 ment. We are dealing in fact, in such cases, 

 with an increase of the ordinary powers and pro- 

 cesses whereby, as we have already stated, the 

 bodily waste is made good. But at the same time 

 we note that these powers and processes vary 

 throughout the animal world, doubtless in obedi- 

 ence to some law which determines the closer in- 

 terdependence of the different parts of animals 

 the higher we advance in the zoological scale. 

 To put the matter in its plainest light, we may i 

 compare the organization of the hydra and its 

 neighbors to that of the " republic." The essen- 

 tial feature of this form of human association I 

 take to be comprised in the broad statement that 

 one man or member of the republic is as good as 

 any other man or member, and that each man 

 (theoretically) has an equal voice with his neigh- 

 bor in the conduct and rule of the state. In that 

 form of government to which the name of " lim- 

 ited monarchy" is applied, the leveling and equal- 

 izing tendencies of the republic are wanting. 

 Every one person is not equal in rank or value to 

 every other person ; but, although each has theo- 

 retically his definite place and voice in the rule 

 and management of the state, some assume a 

 higher rank and power than others. Applying 

 the comparison to the case before us, we can form 

 at least an intelligent conception of the relative 

 nature of the powers of the lower and higher 

 animal. The hydra emphatically represents an 

 animal democracy — a veritable republic. One 

 part is as good as any other part, when demands 

 are made upon it for reparation and growth; and 

 this quality of self-support and independence, 



this power of existing separate from other parts, 

 forms the feature in virtue of which the organi- 

 zation of the hydra becomes so plastic under the 

 most trying conditions, and so well adapted in 

 virtue of its inherent powers to rebuild the dis- 

 organized fabric. In man and higher animals, 

 on the other hand, we find exemplified a form of 

 vital government represented most nearly by the 

 limited monarchy. Here, while each portion of 

 the organism possesses a certain share in the con- 

 stitution and management of affairs, some parts, 

 and notably the nervous system, take precedence 

 of and serve to unite and combine the others. 

 The principle of regulation and interdependence 

 thus involved simply renders it impossible for all 

 parts to possess equal reparative powers. Hence, 

 lost parts are not commonly replaced in higher 

 animals, for the reason that the loss has entailed 

 a separation from other parts, possessing no in- 

 herent powers of reproduction within themselves, 

 and has divided the sustenance and life of the lost 

 parts from that of the entire, connected, and in- 

 terdependent system. 



The process of growth and the harmonious 

 relation of organs and parts, observed in the 

 hydra and in most other living beings, suggest, as 

 a final feature worthy of note, the consideration 

 of what is implied in the growth and increase of 

 living organisms generally. The body of the hydra 

 was, at an early stage of our investigation, seen 

 to be composed of tissues, and these tissues, 

 again, to be made up of minute elements or cells. 

 The growth of the hydra, therefore, in reality, 

 means the increase of each of its minute parts ; 

 and, when we reflect on the law of growth thus 

 evolved, we may be puzzled to account for or 

 explain the intimate nature of the mysterious 

 power which is seen to operate in controlling 

 and directing in so remarkble a manner the func- 

 tions of this humble organism. In the hydra, 

 then, as representing a single organism, or, still 

 better, in the zoophyte, which consists of a colony 

 numbering, it may be, hundreds of animals, united 

 in a close structural relationship, or in the bodies 

 of higher animals still, we find the principle of the 

 perfect cooperation of many different parts to one 

 harmonious end, namely, the maintenance of the 

 organism, beautifully exemplified. In most of the 

 grave affairs of life man strives to secure the co- 

 operation of his fellows ; but humanity, unfortu- 

 nately for the success of its schemes, exhibits many 

 little weaknesses and failings, and the common ten- 

 dency of one mind to assert its supremacy over 

 another may result in the demolition of the coop- 

 erative idea. Man might, therefore, well strive 



