42 LECTURE ni. 



ourselves commence life. They are retained throughout life as an 

 essential part of the organisation of a very extensive tract of our in- 

 ternal mucous membranes ; and these most minute and incalculably 

 numerous vibrating filaments, like their homologues in the Poly- 

 gastria, know no repose. It might almost have been anticipated that 

 this earliest possessed, and most extensively diifused, organical dynamic 

 in every member of the animal kingdom, should be the most conspi- 

 cuous, if not the sole, moving power in the first-born of Fauna. 



Is man liberated from one narrow spot in space, and enabled to 

 move to and fro on the surface of his little world, by virtue of an 

 internal receptacle of nutriment ? So, likewise, is the Infusorial ani- 

 malcule. Even some of the superadded complications of the digestive 

 sac are present ; the Polygastrian seizes food with prehensile organs, 

 reduces it by the action of a score of dental spines, arranged, as we 

 have seen, like the teeth of the circular trephine : it is the very type 

 of the digestive function : assimilating and re-organising the decom- 

 posing particles of animal and vegetable matter with a hundred- 

 stomach power. That low delight, the bliss supreme of the civilised 

 gourmand, is given most liberally where it ought to be, to the crea- 

 tures at the lowest grade of animality. 



Nor is the procreative function so abundantly or so variously en- 

 joyed by any other animal as in the Polygastria : they are fissipar- 

 ous, gemmiparous, oviparous, and viviparous. In creatures whose 

 most obvious and common mode of propagation is by spontaneous 

 fission, a power so actively exercised, as, according to Ehrenberg's 

 experiments, to be productive of an incalculably rapid rate of mul- 

 tiplication, it may be demanded : To what end were special organs 

 of generation developed ? Yet the essential elements of these existed 

 in the Loxodes and Vorticella, and laid the foundation of the ciliated 

 embryos which those species brought forth. If Ehrenberg be cor- 

 rect in his ascription of ova to any of the Polygastria, it is reasonable 

 to suppose that the fissiparous reproduction has reference principally 

 to increasing the numbers of individuals in the infusions, or recep- 

 tacles of decayed organisms, in which they at that time exist ; whilst 

 the development of fertile ova, like the germs in the multiparous 

 pupae of Vorticella, which long retain their latent life in the en- 

 cysted state, have relation to future and different localities or collec- 

 tions of such infusions, into which the ova or germs may be 

 conveyed more easily than the entire animals, and so lay the 

 foundation of new generations of Infusoria. In the heats of sum- 

 mer, for example, many of the pools and stagnant collections 

 of water in which Infusoria abound are dried up. Now, it is true, 

 that certain Infusoria have the power of retaining their vitality 



