266 GENERAL HISTORY OF THE INFUSORIA. 



same class, — as in Spmax vulgaris, ScylUum Canicula, Torpedo Narhe, and 

 Baja Batis, in which the Psorospermia differed from the more usual form, in 

 being grooved or ribbed. 



" It was very remarkable that the above- described organisms were never 

 met vrith in any other part or tissue of the body than the gall-bladder or 

 biliary duct. 



" With respect to the nature of these bodies, Ley dig is inclined to tliink 

 that the cyst should be regarded as belonging to the family of the Gregarince, 

 and that the Psorospermia must be looked upon as generically analogous to the 

 pseudo-Navicellai which have been observed to be generated within the Gre- 

 gariiice. 



*' The question next arises, as to the existence of similar Gregariniform or- 

 ganisms producing Psorospermia in fresh-water fishes. Leydig thinks there 

 is reason to suppose that the animalcule discovered by Yalentin in the blood 

 of Salmo Fario is a Gregarina. Moreover, John Mliller and Leydig have ob- 

 served two or three ecaudate Psorospermia in Leuciscus Dohulst enclosed in a 

 cyst, — whence it might be supposed that secondary cells may be developed 

 within one of Valentin's Haematozoa after it has been conveyed in the coui^se 

 of the circulation to one organ or another, in which cells Psorospermia may 

 originate. With the growth of the latter, the granular contents of the Gre- 

 garinoi gradually disappear, which are thus transformed into cysts filled with 

 Psorospermia. Such a cyst would then be equivalent to a Navicella-recei^- 

 tacle." 



Prof. Huxley, in his Lectures on Natural History (Medical Times, 1856, 

 xxxiii. p. 508) has the follomng account : — 



" The Psorospermia are pyriform sacs, frequently provided with an elon- 

 gated, filiform, motionless appendage, and containing two or foui' clear rounded 

 bodies, attached side by side, within their smaller ends, and besides these, 

 as Lieberkiihn has lately pointed out, a rounded mass of plasma. Under fitting 

 conditions, the Psorospermia burst, and the plasmatic mass emerges as an 

 Amoebiform creature. The sacs in which the Psorospermice are developed, 

 on the other hand, can be traced back to Amoebiform masses full of granules ; 

 and it seems a legitimate conclusion, that the Psorospermia are the pseudo- 

 Navicellce of an Amoebiform Gregarina or Gregarinoid AmoebaJ' 



SUBSECTION II.— CILIATA. 

 (Plates XXIY.-XXXL) 



According to the arrangement we have adopted (p. 200), the Ciliata, as 

 a subsection of Protozoa, are divisible into two groups : — 1. Of such as are 

 mouthless ; 2. Of those possessing a mouth. The former group constitute the 

 Astoma, the latter the Stomatoda. 



In Ehrenberg's system the Astoma were not recognized ; for where he did 

 not find a mouth in any ciliated Polygasirica, he nevertheless assumed its 

 existence, supposing that from its minuteness, or some other cause, it merely 

 escaped observation. This procedm^e was, indeed, rendered necessary by the 

 hypothesis with which he set out, of their polygastric organization. 



It must be admitted, to Ehrenberg's credit, that recent researches have 

 proved him right in assigning a mouth, in by very far the largest number of 

 Ciliated Protozoa, contrary to the assertions and opinions broached by many of 

 the most eminent microscopists a few years since. Yet there is a limited 

 number of mouthless Ciliata, independently of the peculiar family repre- 

 sented by the genus Actinophrys, placed very erroneously in the family 



