106 THE ALTERNATING GENERATIONS 



development in question more widely through nature ; and 

 whilst contemplating it through the phenomena in which 

 it is manifested, we comprehend it in its true light. 



If we collect and regard in one view, the whole 

 system of development by means of " nursing" genera- 

 tions, as it is exhibited in the hell-shaped Polypes [Cam- 

 panularia,) the Claviform Polypes {Coryne,) Medusce, 

 Salpcs, Vorticella, and Entozoa, it appears as a peculiar 

 and consequently as an essential feature in this course of 

 development, that the species (that is, the species in its 

 development) is not wholly represented in the solitary, 

 full-grown, fertile individuals of both sexes, nor in their 

 development, but that to complete this representation, 

 supplementary individuals, as it were, of one or of several 

 precedent generations are requisite. Thus, the distinction 

 between this course of development, and that which is 

 generally recognized in natm^e, in which the species is 

 represented by the individual (of both sexes) and its de- 

 velopment, is the want on the part of the individuals of a 

 complete individuality as representatives of the species, 

 or of a specific individuality, if I may so express it. If 

 now we agree to regard such an incompleteness in the 

 individual, as the essence of this development, we 

 shall comprehend its significance in natm^e when we 

 thoroughly consider this course of development in its 

 various periods, throughout the above-mentioned families, 

 how it begins and advances, so that at last we discover 

 to what it tends. I believe also, that we might trace, 

 even now, this development by means of precedent, pre- 

 paratory generations of " nurses" in its peculiar course and 

 advance, notwithstanding the paucity of instances adduced 

 in the foregoing pages, and the many gaps in the series 

 of observations. Thus we see the greatest incompleteness 

 and the highest degree of mutual dependence in the 

 Campanularice and similar polypes, in which the genera- 

 tions representing the unity of the species are very unlike 

 each other, and in which all the individuals, are fused as 

 it were into an outward unity, or into a set of polypes. . 



