444 RECOKD OF CURRENT RESEARCHES RELATING TO 



Characters of Tristomum Molse.* — Dr. 0. Taschenberg has 

 lately come to the conclusion that this parasite of Orthagoriscus molce 

 is distinct from T. coccineum, with which it is often confounded. It is 

 distinguished not only by the deep constriction at the hinder end of 

 the body, but by the smaller size of the suckers at the sides of the 

 mouth, as well as by other points. The largest examples of the 

 species known to the author are from 13-15 mm. long, and from 

 15-17 mm. broad, and have a rounded form ; the ventral sucker is 

 4^-5 mm. in diameter ; all the specimens examined had their intestine 

 filled with a dark brown mass, whereas in the other species the 

 contents are so slight that it is difficult to follow the course of the 

 intestine. These dark contents seem to be formed by the mucus 

 from the integument of the host, which is intermixed with dirt ; at 

 the same time, T. violce is found on the gills as well as on the 

 integument of the sunfish. 



Loss of the Booklets and Scolex in the Tsenise.f — M. P. 

 Megnin has in a former communication J maintained that the armed and 

 unarmed states of the Tcenue are simply diiferent degrees of develop- 

 ment in the same parasite, and he now offers fresh proofs of this, and 

 also shows that there is a third state quite as constant as the two 

 others to which it regularly succeeds ; this is the aceijJialous state. 



The acephalous state is the index and proof of the cessation of the 

 functions of an organ hitherto regarded as permanent and indispen- 

 sable to the life of the individual — namely, the scolex, or head. The 

 scolex is, however, a transitory organ of the same value as the hydatid 

 cyst ; it is only one of the numerous means of multiplication of which 

 nature has been so prodigal in the TcenicB. 



The Tcenice, when they exist under the form of thehydatid cyst, a form 

 which succeeds to the infusiform embryo, multiply at first (or have a 

 tendency to multiply) by fission. Then appears the germinal mem- 

 brane, index of a second mode of multiplication and of the cessation of 

 the first. This new mode is the multiplication by the scolex, true 

 stolons armed with prehensile booklets and suckers, which come into 

 action as soon as these stolons, sejDarated from the mother vesicle 

 through its destruction, come in contact with an intestinal mucus, or 

 in certain cases with a peritoneal serum. 



At this moment these scolices become the seat of a third method 

 of multiplication, that of buds, which always originate from the point 

 opposite to the crown of booklets, and these buds, adhering to each 

 other, give rise T;o a chaplet or strobila of greater or less length. They 

 are nourished by imbibition, grow, and become sexualized herma- 

 phrodites, when a fourth — oviparous — mode of multiplication com- 

 mences. 



The maturation of the ova coincides in the Tcenice with the detach- 

 ment of the segment which contains them, and which sets them free by 

 its death and destruction of its tissue. The ripening of the ova in 

 most species of Tcenia observed by the author is the signal of the 



* ' Zool. Anzeig.,' ill. (1880) p. 17. 



t ' Comptes Keudus,' xc. (1880) p. 715. 



X See this Journal, ii. (1879) pp. 1G2 aud 878. 



