5 68 



THE LOWEST ANIMALS. 



f 



The spiral-mouthed animalcules (Spirostomum) are among the largest of the 

 class, and visible to the naked eye, especially in sunlight, as slender golden threads 

 about one-tenth of an inch in length. The body is cylindrical, and the surface 



covered with rows of cilia ; the mouth- 

 slit extends along half the length of the 

 \\ I III under side, and is bordered on its left 



side by a fringe of long cilia. The 

 animalcule is frequently twisted on its 

 long axis, the mouth-cilia forming a 

 spiral ; multiplication takes place by 

 transverse fission through the middle. 



The curious marine animalcule 

 Acineta is probably related to the 

 ciliated infusorians. The stalked club- 

 shaped body is usually fixed on sea- 

 weeds or Bryozoa. From the upper end 

 a number of straight sucker -like ten- 

 tacles proceed ; a nucleus and also clear 

 vesicles are present in the bod} r - 

 substancc ; and the embryos are ciliated. 

 The bud -bearing Hemiophrya is 

 also a marine-animalcule ; it possesses a 

 few suckers and a larger number of 

 longer prehensile tentacles; on its margin 

 several buds are formed, each contain- 

 ing a process of the nucleus, and the 

 young forms when liberated are ciliated 

 on their lower surface. The long tentacles capture and disable the prey, and 

 bring it within reach of the suckers, which then surround and dissolve it, and 

 finally appear to pump the newly-acquired nutriment into the general body- 

 substance. 



R. KIRK PATRICK. 



bud-bearing animalcule, Hemiophrya 

 (highly magnified). 



spiral-mouthed animalcule, Spirostomum. a, Nat. size. 



