208 Dr. R. Greef on the Structure and 



If a Stentor be carefully crushed under the glass cover, we 

 see, as the contents of the body flow out, the filaments under 

 discussion projecting here and there isolatedly from the edges, 

 and are able to trace them thence continuously into the remain- 

 ing body. At some points even the filaments are torn on this 

 occasion, and we may then observe how their viscid hyaline 

 substance contracts into thickened bacillar portions. By this 

 the muscular filaments of the Stentors approach very closely 

 to the axial filaments in the stems of the Vorttcellwj with 

 which I should be most inclined to compare these structures 

 as regards their whole appearance, behaviour, and consistence. 



By other artificial methods also, especially by the addition 

 of alcohol, we may ascertain the resistance and independence 

 of the filaments, and that they by no means form a part of the 

 cuticula. 



It would, however, lead us too far from our present task if 

 we were to cite any more details in support of our view. We 

 believe that, from what has been stated, we may attain a con- 

 viction that it is not, as Stein believes, the broad, granular, 

 longitudinal strise, but the narrow, clear, lo7ig{tudinal lines that 

 form the body-muscles of the Infusoria. 



We now revert to our Vorticellaj, and must, in the first 

 place, again refer to the fine transverse strise already mentioned 

 (p. 199), to which, as may be remembered, Stein has ascribed 

 (1st) a spiral course, and (2nd) the properties of muscular fibres. 

 With regard to the first point we have already put forward our 

 doubts, and stated that we think these striae must be regarded 

 as not spiral but circular, and consequently as annulations 

 following closely one upon another. But in the second point 

 also we cannot agree with Stein. The fine external trans- 

 verse strige of the Vorticellse belong rather, in om* opinion, to 

 the external skin, and can by no means be brought, as Stein 

 will have them, into connexion with the longitudinal or mus- 

 cular striae of the Stentors and Spirostomes. The muscles of 

 the Vorticellan body are rather situated beneath the transverse 

 striae, and have, for the most part, a very different course from 

 these, namely in the longitudinal direction of the body, just 

 as is the case also in the other Infusoria. Of this we may 

 best convince ourselves when we examine the hinder part of 

 the body of a Vorticellan under careful compression. The 

 longitudinal fibres, radiating forward from the conical base, 

 make their appearance here very distinctly (PI. XV. fig. 5(/, 

 & PL XVI. fig. 1). They become still more perceptible when 

 we are able to examine an animal separated from the peduncle 

 in such a position that the base of the body is turned directly 

 upwards towards the eye j the fibres are then seen radiating 



