PART I. 



GENERAL AND COMPARATIVE MORPHOLOGY. 



C H A r T E R I . 

 INDI V IDU ALIT Y. 



§ 1. Polarity and PohjcephaUsm. 



1 To those readers who are acquainted with the literature of Acalephce there 

 will very naturally arise, first and foremost, the question as to our theory concerning 

 the individuality of these polymorphic beings. This is a point upon which we feel 

 necessitated at the outset to take a definite stand, in regard to the Acalephm as a 

 whole, and in reference to the Lttcernarice in particular. We have already, in a 

 general work^ upon the development, morphology, and classification of animals, 

 entered our protest against that theory of individuality which assumes that the 

 medusoid genitalia of Hydromedusfe should be considered as individuals in a 

 higher sense than the hydra; are, no matter to how low a degree of development 

 they descend nor at how high an elevation they arrive in the complexity and 

 differentiation of their parts. We still adhere to that protest as far as the hydra? 

 and medusoids are related to each other ; but look upon them both in a modified 

 light in reference to their individuality. 



2 We suppose it will not be questioned that in the main, naturalists and 

 physiologists have always defined in their own minds, and in their teachings, the 

 zoological individual to be a monvcephalic being; that they have taken as their 

 standard the most highly developed creatures of the animal kingdom, whose 

 oneness and independence place them on an equal footing with man in these 

 respects. In the discussion, of late years, upon the individuality of the lower, 

 compound, colonial denizens of the water, the main points at issue have always 

 been to determine whether a certain form was, on one hand, an individual, either 

 in its highest sense (a monomeric, independent integral) or one of several inde- 

 pendent individuals which constitute a colony (a polymeric integer), or, on the 

 other hand, was an organ, which formed only a part of an individual, whether the 



' Miud in Nature, or the Origin of Life and the Mode of Development of Animals. New York, 

 D. Appleton & Co., 18(!5. 



1 February, 1877. t \ ) 



