INFUSORIAL ANIMALCULES. 65 



many exterior warts (gems), without any change in its 

 interior. An animal, which is capable of division, first 

 doubles the inner organs, and subsequently decreases exte- 

 riorly in size. Self-division proceeds from the interior 

 towards the exterior, from the centre to the periphery; 

 gemmation, which also occurs in animals, proceeds from 

 the exterior towards the interior, and forms first a wart, 

 which then gradually becomes organized." (Annals Nat. 

 Hist. v. ii.) 



SECTION XXIV. Vascular System. 



In no creature of this class can a vascular system be 

 satisfactorily demonstrated : that thought to have been 

 such in Paramecium aurelia was merely clusters of ova. 



SECTION XXV. Organs of Sensation. 



Of these, the presence of eyes are all that are demon- 

 strated, though there can be no doubt those of touch, sen- 

 sation, &c., exist. 



In forty-eight species, included under the families 

 Monadina, Cryptomonadina, Volvocina, Astasieea, Dino- 

 bryina, Peridinaea, and Kolpodea, eyes are observable, 

 and the colour of the pigment is red in all cases, except 

 one (Ophryoglena), in which* it is almost black. In con- 

 nection with the visual organs of Amblyophis and Euglena, 

 nervous ganglia have been seen, which constitute the only 

 traces of the evidence of a nervous system. 



