410 THE REPRODUCTIVE FUNCTIONS. 



I 



the fluid, as if animated by two different volitions; and, ap- 

 parently for the purpose of tearing asunder the last connect- 

 ing fibres, darting through the thickest of the crowd of sur- 

 rounding animalcules; and the moment this slender ligament 

 is broken, each is seen moving away from the other, and 

 beginning its independent existence. This mode of sepa- 

 ration is illustrated by Fig. 462, representing the successive 

 changes of form during this progress. In this animalcule 

 the division is transverse, but in others, for example in the 



462 Q 9 8 8 % 



463 



Vorticella, (as shown in Fig. 463,) and in most of the larger 

 species, the line of separation is longitudinal. Each animal- 

 cule, thus formed by the subdivision of its predecessor, soon 

 grows to the size which again determines a farther spon- 

 taneous subdivision into two other animalcules; these, in 

 course of time, themselves undergo the same process, and 

 so on, to an indefinite extent. The most singular circum- 

 stance attending this mode of multiplication is that it is im- 

 possible to pronounce which of the new individuals thus 

 formed out of a single one should be regarded as the parent, 

 and which as the offspring, for they are both of equal size. 

 Unless, therefore, we consider the separation of the parts of 

 the parent animal to constitute the close of its individual ex- 

 istence, we must recognise an unbroken continuity in the 

 vitality of the animal, thus transmitted in perpetuity from 

 the original stem, throughout all succeeding generations. 

 This, however, is one of those metaphysical subtleties for 

 which the subject of reproduction affords abundant scope, 

 but which it would be foreign to the object of this work to 

 discuss. 



