INVERTEBRATA, CRYPTOGAMIA, JriCROSCOPY, ETC. 589 



its inner wall, and attach themselves to the opposite dorsal wall. The 

 concavity caused by the traction of these cords is of course very slight, 

 but nevertheless clearly visible with the Microscope. The animalcule 

 attaches itself to objects by means of this sucker. The surface of the 

 body is covered with very close rows of cilia. Four or five rows may 

 be counted in '01 mm., and in the concavity of the sucker they are 

 half as numerous again. The cilia, whose length is 'OOS mm., are 

 very close together, about thirteen or fourteen in '01 mm. These 

 cilia are the only organs of locomotion, and the progress of the animal 

 is never very rapid. 



The integument or ectosarc has a thickness of • 045 mm., and is 

 composed of two very distinct layers — one external, in which the pro- 

 longation of the cilia may be followed in the form of bacilli, the other 

 internal, composed of transjiarent and absolutely amorphous sarcode. 

 This integument is entirely destitute of proper contractility, so that 

 the animalcule cannot in any way modify its form sjjontaneously ; but 

 on the other hand it possesses great elasticity, which allows the body to 

 resume immediately its normal contour when modified by an obstacle. 

 Theendosarc is composed of clear and liquid sarcode, at the periphery 

 of which exists a layer of large, opaque granulations. 



The nucleus is free in the general cavity, and following the move- 

 ments of the body, can move from one extremity to the other. Its 

 form is that of a very elongate and rather flat ellij)soidal shuttle ; 

 it may measure as much as • 185 mm. Its substance consists of an 

 opaque, slightly yellowish gangue, in which are seen numerous 

 sj)herical corpuscles of nucleolar appearance. When, from the crush- 

 ing of the body, a fresh nucleus is placed directly in the water, its 

 substance contracts, and at the surface there appears a fine amorphous 

 membrane, as in many other Infusoria. 



The body is traversed throughout its length by a long contractile 

 canal attached to the dorsal face, the pulsations of which, from one 

 systole to the next, last a little more tbau a minute. This canal is 

 not rectilinear, but describes numerous sinuosities irregularly disposed. 

 Its diameter in diastole is '018 mm. It is furnished with proper 

 walls, and thus constitutes a true vessel. By this character it difters 

 from the contractile vacuoles of the other Infusoria, which are only 

 temporary cavities hollowed out in the endosarc. The wall of the 

 vessel, visible even in the living animals, becomes still more apparent 

 with coagulating reagents. This vessel, moreover, is provided with 

 orifices, which traverse the integument and open outwards in the form 

 of very clearly visible pores in the midst of the rows of cilia. These 

 pores place the vessel in communication with the exterior, and serve 

 for the exit of the interior liquid at the moment of s^'stole, and very 

 probably for the entrance of the exterior liquid during diastole. The 

 pores, seven or eight in number in the large individuals, are placed 

 exactly in a straight line at irregular distances on the course of 

 the vessel. They are of an oval form, and measure '003 mm. in 

 length. 



This Infusor multiplies by dividing transversely into segments. 

 The segmentation is at first indicated at the middle of the length of 



VOL. II, 2 R 



