474 ON DYSTERIA 



the dimensions of the latter vary from the size given above to one- 

 fourth or less, no relation could be observed between this diminution 

 and the presence of the granules in other parts of the body. 



Behind the amethystine globule the substance of the body has the 

 appearance, common to the Infusoria generally, of a mass of " sarcode,"" 

 in which the ingested matters are imbedded, and no clear evidence 

 could be obtained of the existence of any digestive cavity with 

 distinct walls. 



A little behind the middle of the body, and towards its ventral 

 edge, there is a clear spheroidal " contractile space " (d), which varies, 

 a good deal in size. One measured xs-Voth of an inch in diameter,, 

 and became entirely obliterated in the contracted state. 



The contractions are not rhythmical, but take place irregularly. 

 On the approach of death the space becomes irregularly and enor- 

 mously enlarged, until it occupies perhaps a third of the whole 

 contents of the body. 



Immediately beyond the contractile space there is a curious oval 

 body (e), having its long axis (toVo in-) directed upwards, and con- 

 taining a comparatively small central cavity, so that it appears like a 

 thick-walled sac. 



Indications strongly suggestive of an inferior opening were some- 

 times observed in this body, but no demonstrative evidence of the 

 existence of any such aperture could be obtained. 



The walls of the ventral groove are provided with long and 

 powerful cilia, a remarkably strong one being attached behind the 

 base of the " appendage," and by their means the animal, when free,. 

 is propelled at no very rapid rate through the water. Its more usual 

 habit, however, is to remain fixed by means of the peculiar appendage 

 (/), and then the cilia act merely in creating currents, by which 

 nutritive matters are brought towards the mouth. 



The appendage referred to is attached to the surface of the body,, 

 rather towards the convex side, at the bottom of the ventral groove, 

 and is distant about one fifth of the whole length from the posterior 

 extremity. It is ^oth to xoVuth of an inch in length, and is not 

 altogether unlike a boot, with a very pointed toe, in shape ; and the 

 toe appears to be viscid at its extremity, so as readily to adhere to any 

 foreign object. The appendage then forms a pivot on which the whole 

 body turns about, and this appears to be the habitual and favourite 

 position of the Dysteria. 



Internally, the appendage contains a canal {g) wider above than 

 below, and apparently blind at each extremity. 



No " nucleus " could be found, though carefully sought for with 

 the aid of acetic acid. 



