182 ANIMAL PAEASITES. 



Zeder's case also appears to have been one of true Cyst, 

 tenuicollis, so that all the cases do not deserve the negative 

 criticism of authors, down to Virchow. Eschricht, who has 

 done such good service in reference to the Cestodea, mentions, 

 as cases of true Cystic, tenuicollis, two cases which occurred at 

 a very recent period, and which are both to be met with in 

 Schleissner' s 'Nosography of Iceland/ I am sorry that I must here 

 contradict the respected Danish naturalist, and acknowledge that 

 I can only regard the case observed by Schleissner himself as a 

 true Cystic, tenuicollis, whilst llhorstensohn refers to an Echino- 

 coccus hominis autorum, or more correctly Echinococcus altrici- 

 pariens (mihi), from the liver. Thorstensohn's case, according to 

 Schleissner, is as follows : " A boy of four years old had suffered 

 for several months from a swelling of the right side of the abdo- 

 men, with subsequent dropsy, and at the same time also from the 

 passage of Lumbrici and Ascarides through the anus. On the 

 right side there was a fluctuating swelling as large as a child's 

 head, which, when opened, gave issue to a quantity of fetid, thin 

 matter, with a number of hydatids as large as pigeons' eggs." 

 That this case refers to an Echinococcus will be admitted by every 

 one who has ever seen one with daughter- and granddaughter- 

 vesicles of every grade of development in which the cyst-walls of 

 the daughter-vesicles possess the thickness and elasticity, and, in 

 consequence, the property, caused by imbibition, of moving in 

 lukewarm water in an undulating manner. This is also shown 

 by the fact that the cyst of a Cysticercus, even if it should 

 attain the bulk of a child's head, never contains more than one 

 scolex, in, or rather on, the vesicle which it encloses. What- 

 ever number of Cysticerci may exist in the abdomen, there 

 is always the same number of separate enveloping cysts, even 

 when, as I saw in one case in a pig, which had not been artifici- 

 ally infected, their number on the mesentery alone amounted to 

 eighty. Even here I did not see the absorption of the walls of 

 two approximated cysts, so far advanced, that one cyst might 

 have enclosed two Cysticerci. If therefore we pierce such a cyst, 

 masses of uninjured hydatids cannot flow out, as in Thorstensohn's 

 case, but this refers to another kind of worm, which can only 

 be an Echinococcus. Thus an uninjured vesicle never issues from 

 the pierced or cut cyst of a Cysticercus, but only an injured one. 

 Eschricht has probably allowed himself to be led to the supposi- 

 tion that a Cystic, tenuicollis is treated of by Thorstensohn, by 



