390 Zoological Society. 



The commonly received view of the relation between the cysts and 

 their Echinococci appears to have been first advanced by Delle Chiaje 

 in his Elmintoyrafia Umana, p. 30*. 



" The said worms, oval, narrowed at the two extremities and en- 

 larged in the middle, are scattered irregularly over the interior of the 

 vesicle. The extremity of the head is garnished with a crown of books 

 deprived of suckers. In proportion as they enlarge, these little micro- 

 scopical bodies take on, little by little, a spherical form, the hooks 

 become detached, and new Echinococci are produced in such little 

 bodies, which have transformed themselves into Hydatids. The new 

 worms are the children (figliuolini) of the primitive Hydatid, which 

 was a similar microscopic body. They have a proper vitality, different 

 from that of the vesicle which contains them." 



Muller, ' Jahresbericht,' 1836, describes the Echinococcus-cjsts 

 and their contents found in the urine of a young man labouring under 

 renal disease. 



The cysts had a laminated outer coat ; some contained Echinococci 

 and some none, but in other respects they were completely alike. The 

 Echinococci exactly resembled the ordinary figures. 



" In a few of the free ones, a trace of a membranous cord, looking 

 as if it had been torn off, appeared at the posterior end of the body ; 

 as if the worms had at an earlier period been fixed." 



Muller could not make out whether the Echinococci were fixed to 

 the interior of the secondary vesicle or not. 



Tschudi, 'Die Blasenwurmer, 1837,' observed the retrograding 

 yellow Echinococci, which he assumes to be returning to the vesicular 

 form. He considers that the " corpuscles " are ova, and that by their 

 development in the interior of one of these retrograded Echinococci, 

 the secondary cysts are formed. 



Gluge, 'Annales des Sciences Naturelles, 1837,' describes the 

 corpuscles of the Echinococci very carefully and minutely. He was 

 the first to notice the peculiar structure of the endocyst. He says, 

 " I have constantly seen in it a kind of arborization very similar to the 

 formation in fibrinous exudations during the first stage of inflamma- 

 tion. We see these transparent bodies with slightly irregular contours 

 resembling empty blood-vessels and ramifying like them. I do not 

 know whether these are true vessels, I merely draw attention to 

 the fact." 



In the same year (1837) the second edition of Burdach's 'Physio- 

 logie' appeared. It contains an admirable chapter by Von Siebold, 

 upon the development of the Entozoa. Burdach's work is so little 

 known, and so inaccessible in this country, that I think it worth while 

 to subjoin the whole of what Von Siebold says upon this subject : — 



" In the development of the Echinococci also, much has remained 

 obscure. We must in them always distinguish two things ; the pa- 

 rent vesicle, and the proper Echinococci enclosed within this. The 

 maternal vesicle is covered internally by an excessively delicate epi- 

 thelium, in which arc contained corpuscles similar, though here 



* Compentlio di Elmintografia Umaua. Napoli 1825. Compilato da Stephano 

 Dclle Chiaje. 



