PROTOZOA. 57 



tracted portion of the tube beyond is the esophagus 

 proper. As yet the digestive system is not complete, 

 there being no separate opening or anus on the surface 

 for the exit of waste matter. If the Vorticella is given 

 carmine or indigo, the way the food is caught by the 

 cilia (which are borne on the thickened rim or peristome 

 surrounding the disc of the bell) and its circulation 

 through the ciliated vestibule and esophagus and through 

 . the endosarc of the body to its exit at the mouth, can all 

 be observed with the microscope. With the differentia- 

 tion of the muscular and digestive systems there is a 

 greater specialization in the reproductive system and in 

 the processes which lead to increase. PI. 56, figs. 1-29, 

 taken from Everts, 1 illustrate the process of reproduction 

 through longitudinal fission, and figs. 30-34, after Greef, 2 

 the process through the conjugative act. Beginning with 

 the little ball (fig. i) which issues from the cyst, we find 

 it a tiny mass of protoplasm showing no differentiation. 

 It agrees structurally at this time with a cytode, since no 

 cell wall is discovered, and it is not until the cilia are 

 developed that it becomes a cell with a nucleus. A vac- 

 uole appears (fig. 2), next a swelling (fig. 3). and a wreath 

 of cilia (fig. 4). The form changes and an organism 

 appears which is likened by Everts to the Trichodina 

 grandinella described by Ehrenberg. 



This Trichodina (fig. 5) continues to grow (figs. 6-9) 

 until transverse constriction takes place with a separation 

 into two Trichodinas (fig. 10). Then the body lengthens 

 (figs, n, 12) with the formation of the peristome (fig. 13), 

 after which the stem is secreted (figs. 14-17). Fig. iya 

 represents a stemmed Vorticella much enlarged. This 

 form contracts (fig. 18), the body broadens (fig. 19), and 

 the nucleus takes a position at right angK s to the stem. 

 A constriction takes place (fig. 20) which increases (fig. 

 21) until the division is complete (fig. 22). A wreath of 



'Zeitschr. f. wiss. Zool., XXIII, 1873. ' 

 2 Arch. f. Naturg., XXXVI, I, 1870. 



