ANIMAL PARASITES. 15 



tioned at that time under the name of hydatids, which were then 

 considered sometimes as enlarged and degenerated glands 

 (Ruysch) ; sometimes as accumulations of pus and mucus mixed 

 with serum (Piso, Malpighi, Boerhave, Haller) ; sometimes as the 

 ends of blood-vessels which had changed their nature (Spiegel, 

 Bartholin, Diemerboock, Portal, Brandes, Grashuis) ; sometimes, 

 soon after the discovery of the lymphatic vessels by Aselli in the 

 seventeenth century, as enlarged lymphatic vessels or varices of 

 these vessels (Wharton, Bidloo, Nuck, Lettsom, Cruickshank, 

 and down to Sommering and Hufeland) ; and sometimes as 

 tumours produced by the accumulation of serum between the 

 laminae of the cellular tissue, which obliterated the vessel lying 

 in their vicinity by pressure (Ruysch and Schacher) ; and lastly, 

 as degenerated mucus-sacs (Tode). Although it may generally 

 be difficult from these opinions amongst the learned surgeons of 

 the Middle Ages to know, when they speak of hydatids, whether 

 true hydatids or cystic worms were observed by them, yet in 

 some cases it may be proved with certainty that the old surgeons 

 really had cystic worms before them. Thus according to Moller 

 (see 'Bibliothek for Laeger/ July, 1856; 'Ueber die Entwickelung 

 der Blasenwiirmer zu Bandwurmern im Allgemeinen und iiber 

 die Entw. des Cystic, tenuicoll. zu T. tenuicoll. im Besonderen/ 

 &c.) Aretseus speaks of vesicles which, in paracentesis of 

 the abdomen, stopped up the punctured opening and hindered 

 the operation (a circumstance which would indicate the puncture 

 of an Echinococcus-sac with daughter-vesicles). R. Leuckart, 

 however (see ' Die Blaseiibandwiirmer und ihre Entwicklung/ 

 Giessen, 1856), has above all taken the trouble of collecting some 

 of these very scattered materials. For this purpose, according to 

 him, we should consult the celebrated compilation of Bonetus 

 (' Sepulchretum sive Anatomia practica/ Geneva, 1697), especially 

 lib. iii, sect, xx, de cachexia, anasarca, &c., and sect, xxi, de ventri 

 tumore, hydropse, and lib. iv, sect, iii, de tumoribus. There we 

 shall find the case of a soldier infested with Cysticercus celluloses 

 from Wharton (1. c., p. 1541), who was covered with Cysticerci 

 (glandul. adventitia, plane sance) under the skin of the arms and 

 thighs (a case analogous to that observed by Stich in the 

 Hospital of Romberg). Here also, as in Platerus (Obs., lib. iii, 

 p. 635), we find indications of cases of Cysticercus tenuicollis in 

 the liver and peritoneum of dropsical human bodies, and the 

 occurrence of these tumours (Cyslicerci] in apes and pigs was 



