120 Excerpta Zoologica : Metamorphoses of Intestinal Worms. 



longed neck of the worm extended into the cavity of the tail. At 

 the end of the neck there is an incurvation which might be regarded 

 as the mouth. I perceive in the drawing of Leblond a distinct aper- 

 ture at the same place. Of the great sucking head which Leblond 

 asserts his having seen on the body of this worm, to which he has 

 applied the name of Amphistoma ropaloides, there is no mention in 

 Miescher's description. Miescher further observed, on the rede- 

 velopment of the tail, that the neck of the worm withdrew itself 

 within the expanded head and gradually disappeared entirely ; in the 

 simple oval cysts he then found an oval, somewhat flattened trema- 

 todoid worm, at the front margin of which the incurvation suspected 

 to be the mouth was more distinct. This worm consisted of a trans- 

 parent homogeneous substance, with round large and small granules 

 scattered in it, without the slightest trace of any distinct internal 

 organs : its vermoid motions, even though sluggish, did not allow of 

 the least doubt being entertained as to the independent animality of 

 this worm. Miescher did not hesitate to suspect that the chrysaloid 

 bodies were derived from the Filaria, although he did not observe 

 directly the metamorphosis of a Filaria into a clavate body. Miescher 

 adduces the following reasons in support of his supposition : the ru- 

 dimentary organs of generation of the Filaria indicate that these ani- 

 mals have not yet reached their full development ; the clavate bodies 

 occurred with the Filaria in the very same place ; Miescher saw whole 

 nests of clavate bodies and Filaria inclosed by a common cyst, in 

 which large and small Filaria, with and without tails, occurred. In 

 the three different genera of fish on which these inquiries were made, 

 in Trachinus, Gadus and Trigla, the Filaria, and also the clavate bodies, 

 presented complete specific differences. 



The trematodoid worm appeared now to develope anew, while the 

 substance of the Filaria, with the exception of the epidermis, dissolved 

 into nutriment for the new creature. Miescher found the posterior 

 extremity of the Filaria to be the point of development of the new 

 worm. A Tetrarrhynchus gradually formed in the hinder portion of the 

 body of the trematodoid worm, while the first worm still continued 

 to live and did not quit its envelope. The Tetrarrhynchus, which was in 

 no way in organic connexion with the trematodoid worm, lay bent spi- 

 rally together in its cavity, and showed by its retraction and exsertion 

 of the four snouts, and by the rotation of its body, signs of its inde- 

 pendent existence. Leblond likewise observed in the tailed bodies 

 a similar Tetrarrhynchus, which he considered to be the Tet. appen- 

 diculatus, Rud. Miescher makes no mention of the appendage which 

 Leblond observed on this worm. Miescher found in a Trigla Gur- 

 nardus, in the month of March, together with living Filaria and cla- 

 vate sacs, tailless sacs, most of which were empty and only contained 

 a mucous granular substance. On further examination he detected 

 in the ventral cavity some Tetrarrhynchi which had just escaped ; 

 but was greatly surprised, on opening the pericardial cavity, to find 

 this swarming with Tetrarrhynchi, and the heart full of them, which 

 was the more remarkable, as Miescher had never met with Filaria or 

 clavate bodies in this cavity. The Tetrarrhynchi of this place were 

 characterized by a short appendage to the extremity of the body, 



