474 GENERAL HISTORY OP THE INFUSORIA. 



do not see that this circumstance is per se adequate to establish an alliance 

 with the Insecta, particularly when, in most other respects, the differences 

 between the two groups of beings are so very considerable. Heferring only 

 to the particulars mentioned in Vogt's critique, we may observe that if the 

 aberrations of organization of Eotatoria from the lowest Crustacea render 

 their alliance with the latter more than doubtful, still less possible is their 

 connexion with the highest Articulata, in which every differential character 

 becomes more developed. 



The arguments and illustrations of Yogt in favour of the close affinity 

 of Rotatoria with Vermes will to most minds appear convincing ; but should 

 any demand further evidence, it is supplied by the opinions of the majority 

 of naturalists and by the reasons adduced in their support. At present we 

 will confine ourselves to the views and arguments of Perty, Siebold, William- 

 son, and Huxley. 



Perty enters into no discussion, but merely states generally that the posi- 

 tion of Rotifera with Vermes is indicated by their want of jointed feet in 

 pairs, and of a ganghonic abdominal chain such as Crustacea have, whilst, on 

 the contrary, they are provided with external voluntary and internal invo- 

 luntary cilia, after the type of Vermes. The class to which he would refer 

 them is that of the Thoracozoa (Arthrozoa). 



Siebold affirmed that the affinity of Rotifera ^\\ih. the Crustacea is but 

 remote, since they are, he conceives, deficient of a distinct abdominal mem- 

 brane, of limbs in pairs, and of striped muscular fibre, — undergo no meta- 

 morphosis like Crustacea, — have organs of respiration (ciha) both externally 

 and internally, and an epithelium lining the alimentary tube, such as no Ar- 

 thropoda or Cnistacea possess. Subsequent research has invalidated a few 

 of the reasons put forward by Siebold, such as that of the absence of striated 

 muscles ; but the majority retain their force. 



Prof. Williamson argues, from the particular instance of Melicerta, against 

 a Crustacean relationship. His words are — '' In the possession of so highly- 

 organized a form of voluntary muscle, in the investment of the fasciculi by a 

 sarcolemma, and in the existence of a well-defined, ciliated, cellular epithe- 

 lium lining the alimentarj^ canal, we have indications of an organization ap- 

 proaching that of the lower Articulata. The dental apparatus appears to 

 constitute a splanchno-skeleton, like that of the Crustacea ; but, on the other 

 hand, the absence of a visible nei'vous system removes the Melicerta far below 

 the Homogangliate animals. That they should possess a nervous system of 

 some kind appears almost a matter of necessity if the presence of a striated 

 muscular fibre indicates volition ; but its actual existence has yet to be de- 

 monstrated. I have found no special organs of circulation or respiration. On 

 watching the movements of the small free cells which float in the visceral 

 cavity, as well as in the tail, it becomes obvious that the fluid contained 

 within the integument moves freely Avith every contraction of the body. I 

 detect no vessels or pulsating organs. These facts also tend to associate the 

 animal with the Acrita rather than with the Homogangliate Crustacea. At 

 the same time its organization is of a higher type than that of the Bryozoa. 

 . . . .Again, many Vermes possess horny jaws not wholly imlike those of 

 Rotatoria, together with similar stomach-glands, equally resembling those of 

 some lower CiTistaceans ; and, moreover, many Vermes, e. g. Clepshie, carry 

 their eggs about with them." 



Prof. Huxley has very ably examined the question of the affinities of the 

 Rotatoria. Containing, as his opinions and illustrations do, many additional 

 facts, we shall, at the risk of some repetition, add them to the preceding dis- 

 cussions and details. In the first place, he adopts, as a group of the lower 



