218 Dr Gairdner's Analysis of 



These great longitudinal muscles are distinct to the most un- 

 practised eye, but Dr Ehrenberg views as of a muscular charac- 

 ter, 1 . The seventeen sections of the rotatory organ in the Hyda- 

 tina, which must be the principal agents in directing the motions 

 of the ciliae ; 2. A contraction or sphincter near the extremity of 

 the cloaca; 3. A striated organ behind the cloaca, which he 

 considers, from its situation, as an acceleration of the seminal 

 fluid, a musculus ejaculatorius. In none of these, however, ex- 

 cept the last, can the existence of a fibrous tissue be considered 

 as beyond a doubt ; though, from their situation, it is more 

 than probable that this is their true nature. All of these parts 

 seem to be attached to the inner layer of the external double 

 membrane, and to be unconnected with the subjacent viscera. 

 It is not improbable that the tail may possess some proper 

 muscles, as its motions are not performed laterally in common 

 with the trunk, but by an alternate retraction and elongation. 



3. Generative System. — The partizans of the generatio spon- 

 tanea vel primitiva, who so long stood their ground in the class 

 of Entozoa *, after being forced to relinquish this position, by 

 the discovery of the ova of these parasitic animals, took refuge 

 in the darkness and obscurity of the microscopic infusoria, where 

 they were almost secure of an undisturbed possession, while 

 there was nothing known concerning them except as a -homoge- 

 neous mass of transparent jelly, endowed with a few active 

 motions ; and where their negative arguments could only be at- 

 tacked by analogical reasonings. 



The candid and impartial mind of Miiller himself, too rigid 

 an observer to be seduced by the allurements of theory, con- 

 sidered the infusory animals as furnishing an incontrovertible 

 argument for the existence of certain living forms, which are 

 neither of oviparous nor gemmiparous origin, but derive their 

 existence immediately from a certain indestructible living gene- 

 rative energy inherent to all matter ; — for this very plain reason, 

 that he had never witnessed the secrets of their origin. Such a 

 conclusion, though perhaps too hasty, is allowable in such an 

 observer. When, ho^vever, we see other men of distinguished 



• We are surprised that this class should still be ranged under its ancient 

 category by the anatomical school of Halle. 



