306 GENERAL KISTORY OF THE INFUSORIA. 



cess is broad and foliaceous, and bears the rows of cilia on the margin, whilst 

 the anus is placed far up on the dorsal suiface of a thin plate. In the other 

 genus, Chcetosjoira (Lachmann), observed by me in fresh -water near Berlin, 

 the process is narrow and bacillar ; the series of ciHa commences at its free 

 extremity, and only forms a spiral when in action by the rolhng up of the 

 lamina ; in this genus also the process bears the anus. In both, faecal masses 

 which are thicker than the process in its extension, pass through it to the 

 anus, without breaking through it, notwithstanding the great expansion of 

 its walls. 



*< Not unfrequently several balls of excrement unite into a large mass 

 before the anus, in order to be passed out together. When an excretion takes 

 place, the anus is seen to open (but often closes once more and opens again 

 before the expulsion of the masses is effected), and then the fsecal masses are 

 often expelled slowly." 



He further deseribes the situation of the anus in Ehrenberg's Oxytrichina 

 and Eiqylota, in Colpodea with the exception of the species of Amjphileptus 

 and U^'oleptus, in the Cydidina, and in Glaucoma, Trachelius, Chilodon, and 

 Nassula, to be on the ventral surface near the posterior extremity, or at the 

 posterior extremity itself. In Bursaria and Spirostoinimi it is placed at the 

 posterior extremity, as also more commonly in Colejps, Enchelys, and Trache- 

 locerca. In the Stentorma it occiu's on the back close beneath the series of 

 ciha, and in Chilodon CucuUidus it is nearly on the right margin of the body 

 near the hinder end. Among the true Vorticellina and Ojphrydina the anus 

 opens into the vestibule very close to the oral aperture, a stout curved bristle 

 being placed between the two (XXIX. 2 e, i). 



Excepting on this point of a preformed, constant, and definite discharging 

 orifice, there is among microscopists an almost universal accord in the pre- 

 ceding account of the phenomena connected with the reception and digestion 

 of food. It would be a useless expenditure of space to insert even an 

 epitome of the observations and arguments of only the most eminent of 

 modern naturalists who coincide with it ; it will be sufficient to cite their 

 names and their contributions on the subject : — Meyen, in Edinh. Phil. Journ. 

 vol. xxviii. ; Dujardin, Histoire des Infusoires, 1841 ; Siebold, Anatomie der 

 Wirbellosen Thieve, 1848 ; Boek, Ohen's Isis, 1848 ; Wagner, Zootomie, sect. 

 Infusoria, 1848 ; Yan der Hoeven, Lehrhuch der Zootomie, 1850 ; Leuckart, 

 in Van der Hoeven's new edition, 1856; Stein, Die Infusionsthiere, 1854; 

 Lachmann, "On the Organization of the Infusoria,'' A. N.H. 1857,xix. ; Carter, 

 Huxley, and Carpenter ; indeed, all British authorities, with whose works we 

 are acquainted, who have written on the subject. This is certainly a long 

 array of authorities against Ehrenberg's theory of poly gastric organization ; 

 and almost the only advocate he has found on his side is Eckhard, once a 

 pupil of his own. This gentleman has published some observations which 

 seemed confii^matory, but are undoubtedly erroneous in several particulars. 

 The follo^ving remarks, bearing specially on the subject at present under con- 

 sideration, may be quoted : — 



He writes — " In such forms as are not too minute, we can distinctly see 

 how the nutriment, artificially supplied, constantly takes a definite course in 

 the body : in some instances the first portion of the ahmentaiy tube can, 

 when not in action, be observed, as in Epistylis grandis ; it is then frequently 

 seen to be covered on the inner surface A^dth cilia, which, in the Opercularia, 

 may even be counted. But that this alimentary canal does not, after a short 

 course, terminate abruptly in the body, can also be proved in the Epistylis 

 grandis. 



** In this animalcule a portion of colouring-matter swallowed is seen to 



