362 EVENINGS AT THE MICROSCOPE. 



protruded from the cinclides, and many more of the latter 

 widely open. The acontia, in some cases, did not so ac- 

 curately fill the orifice but that a line of bright light (or 

 of darkness, according as the sun was exactly opposite 

 or not) was seen partially bordering the issue of tin- 

 thread, while the thickened rim of the cinclis surrounded 

 all. 



The appearance of the orifices whence the acontia 

 issued was that of a tubercle or wart, and the same ap- 

 pearance I have repeatedly marked in examples observed 

 on the stage of the microscope ; namely, that of a per- 

 forate pimple, or short columnar tube. This was clearly 

 manifest when the animal, slowly swaying to and fro, 

 brought the sides of the cinclis into partial perspective. 



On another occasion I witnessed the actual issue of the 

 acontia from the cinclides. I was watching, under a low 

 power of the microscope, a specimen of a S. nivea, while, 

 by touching its body rudely, I provoked it to emit its 

 missile filaments. Presently they burst out with force, 

 not all at once, but some here and there, then more, and 

 yet more, on the repeated contractions of the corrugating 

 walls of the body. Occasionally, the free extremity of a 

 filament would appear, but more frequently the bight of a 

 bent one ; and very often I saw two, arid even three, issue 

 from the same cinclis. The successive contractions of the 

 animal under irritation, caused the acontia already pro- 

 truded to lengthen with each fresh impetus, the bights 

 still streaming out in long loops, till perhaps the free end 

 would be liberated, and it would be a loop no longer ; 

 and sometimes a new thread would shoot from a cinclis, 

 whence one or two long ones were stretching already : 

 while, as often, the new-comers would force open new 

 cinclides for themselves. The suddenness and explosive 

 force with which they burst out, appeared to indicate a 

 resistance which was at length overcome : — perhaps (in 

 part at least) due to the epithelial film above mentioned, 



