104 L. Stieda on the Taeniae. 



orifice, but subsequently only O007-O014 mill., represents the 

 vagina. Close behind the end of the cirrus-pouch which is 

 turned towards the median line of the joint, this canal becomes 

 suddenly dilated to the considerable size of 0070 mill. : the 

 limits of this dilatation escape detection in the vicinity of the 

 germ-stock and yelk-stock; so that it would appear as if the 

 dilatation pushed itself in between those organs. I have not 

 been able to discover any connexion between the dilatation of 

 the vaginal canal and the germ-producing organs. The con- 

 tents of this dilatation consist, as may easily be ascertained, of 

 seminal filaments; so that we have to do, according to this, only 

 with a remarkably extended seminal pouch of the vagina, or a 

 receptaculum seminis. 



Whilst now the receptaculum serninis becomes more and more 

 filled by increased reception of semen, and the germ- stock and 

 yelk-stocks become more and more extended, the testes undergo 

 a retrograde metamorphosis, and gradually disappear. 



At about the 150th joint the first indication of the uterus 

 makes its appearance. Both at the upper margin and at the 

 two lateral margins the uterus appears as a cavity in the paren- 

 chyma of the body, furnished with diverticula and filled with a 

 mass resembling the contents of the yelk-stocks. The following 

 joints present the different degrees of development of the uterus, 

 whilst the other organs gradually disappear. Towards the end 

 of the second hundred segments, in which the uterus is shown 

 in its full development, of the other organs only the cirrus-pouch 

 and vaginal canal, with the receptaculum seminis, are retained ; 

 the latter organs are completely pressed down to the lower mar- 

 gin of the joint, and have considerably diminished in extent. 

 The form of the uterus is characteristic, in that its principal 

 stem, corresponding with the short but broad form of the pro- 

 glottides, runs transversely, whilst the lateral branches or the 

 individual diverticula are arranged in the direction of the length 

 of the joint. 



As the development of the ova was not sufficiently observed 

 by me, I only add a few words upon the mature ova found in 

 the last proglottides. These appear smooth and perfectly round; 

 they are 0035-0042 mill, in diameter, and possess two enve- 

 lopes, of which the outer one, 00035 mill, in thickness, presents 

 a stratified appearance, whilst the other, which is closely applied 

 to the embryo, on which the embryonal hooks are scarcely visi- 

 ble, appears to be very fine and structureless. 



In the small intestines of the Field-Mouse there was some- 

 times, although but rarely, another Tcenia, to which I here refer 

 because it perfectly agrees, in regard to the genital apparatus, 

 with the T. umphalodes. I am not in a position to make very 



