244 T. W. Eiigelmanii on the Infusoria. 



same time two curved longitudinal folds make their appearance, 

 extending backwards or inwards from the newly formed wreath 

 of adoral cilia, constituting the boundary of a new peristome, 

 which proceeds to develope as the old one progressively vanishes 

 along with its surrounding cilia (PI. III. figs. 2, 3). Even after 

 the separation of two of these peculiarly conjugated animalcules, 

 many of the characteristics of the usual forms of Euplotes Charon 

 are deficient, one of the most remarkable of which is the absence 

 of a mouth ; for the adoral cilia end at the middle of the area of 

 the peristome, and the two folds indicating this structure coalesce 

 so as to constitute a rib-like elevation ending at the base of the 

 fifth posterior cilium. Moreover the ventral surface is traversed 

 by a distinct fold, not seen or very slightly developed in animals 

 of the ordinary type. The most striking variation, however, in 

 the new being is witnessed in the nucleus, which divides into 

 two portions either before or simultaneously with the commence- 

 ment of the formation of the new ciliary appendages in the con- 

 jugated animals. One segment is anterior, and much larger 

 than the other, and occupies the whole anterior third of the 

 ventral cavity, whilst the other, globular in figure, is thrust 

 backwards and to the left side. The nucleolus undergoes fission 

 yet earlier, and one section of it continues in apposition with 

 each portion of the nucleus. After the separation of the animals 

 a pale discoid body is noticed near the posterior extremity and 

 on the left side, which gradually advances more forward and to 

 the centre, and acquires an increased diameter and transparency, 

 until at length it forms a perfectly clear, somewhat compressed 

 spherical body, filling ofttimes two-thirds of the whole interior 

 of the animalcule, and occupied by an extremely fine, granular, 

 homogeneous substance (fig. 3). Beside or behind this body, 

 a considerable portion of the original nucleus is noticeable, toge- 

 ther with a constantly fluctuating number of larger and smaller, 

 strongly refracting (fat ?) corpuscles. Two or three days, or 

 thereabouts, after the separation of the two individuals, they are 

 found to have re-assumed the customary form and structure of 

 the species, including the peristome, mouth, and the original 

 horseshoe-shaped nucleus. 



The question suggests itself, What is the origin of the large 

 transparent globule in the interior, and what purpose does it 

 serve ? To this question Engelmann is at present unable to give 

 a decisive answer. He is in doubt whether this corpuscle origi- 

 nates from the posterior half of the nucleus after its fission, or 

 whether it takes its rise prior to the detachment of the conju- 

 gated animals, as an independent formation from the nucleus. 

 The latter assumption derives support from the circumstance 

 that, in two conjugated individuals on the point of separating, 



