TRICHINA SPIRALIS. 347 



lines of 0'016 mill, in length on an average, which have usually 

 been described as a little cleft, but have also been regarded as a 

 mouth. From the cylindrical form of the worm, we certainly 

 only see one cleft, but if the worm be allowed to move, or another 

 position be given to it during examination, by shifting it about, 

 we are convinced of the existence of three clefts. These three 

 clefts, however, are the expression of the presence of three valves, 

 which the animal can open and close at pleasure. If these valves 

 bend back, a portion of the tube protrudes, and produces an 

 appearance as if the worm were torn, until the valves close and 

 the ordinary form returns." Finally, Luschka concludes with 

 the following leading sentence, which is even rendered particu- 

 larly prominent by the mode of printing : " It is quite indubitable 

 that in Trichina all the tubes in the cavity of the body have free 

 extremities, and that their contents are only separated outwardly 

 by the opening of these valves." 



I have not been able to come to this conclusion. The pressure 

 employed by Luschka, which was often very strong, certainly led 

 him here to mistake the true state of the case. There is no 

 doubt that the intestine passes directly, through a sort of simple 

 cleft, into ths anus. The authors who speak of this cleft are 

 perfectly in the right. But at the extreme end of this cleft there 

 is an apparatus, which might certainly be called valvular. At all 

 events, in the mature state, these valves may probably still be 

 indicated in the females, and form that button-shaped process at 

 the extremity of their abdomen in which the anus opens, and 

 which I have represented in Plate VII. From these valves in 

 the male, however, might probably be developed the spinous 

 copulatory appendage, which still plainly bears at its extreme free 

 end the traces of a previous lobate organ, as it appears to be 

 composed of several leaves. Although I thought I usually 

 observed four segments in the copulatory appendage, I may have 

 been under a mistake. At least I could not make out clearly 

 whether this organ consisted of three or four leaves, although I 

 adopted four as the more probable number. 



Luschka supposes the intestine to hang freely in the interior 

 of the membranous cylinder formed by the worm, and sometimes 

 to lie close to the inner wall of this cylinder and sometimes at a 

 distance from it, which then essentially alters the appearance of 

 the object, and also confirms this view by the circumstance that 

 it is easy to strip off the skin partially or wholly when tearing or 



