214 ON THE ANATOMY OK THE ECHINOCOCCUS VETERINORUM 



a cyst which contains Echitwcoccus-cysis, secondaiy cysts are formed> 

 which, after they have attained a certain grade of development, be- 

 come detached from the inner wall of the larger cyst, and fall freely 

 into their cavities, but still show the remains of their attachment in 

 a slightly pointed place : on the inner surface of these secondary 

 vesicles tertiary ones are now formed in the same manner, and so on. 

 The hydatid sacs then arise b\- a kind of endogenous formation similar 

 to that which Prof Miiller has already so beautifully described in the 

 development of a peculiar kind of hydatid tumours (BalggeschwUlste "). 



In his Article " Parasiten " (Wagner's Handworterbuch d. Phy- 

 siologie, bd. 2, 1844), Von Siebold, after recapitulating his view of 

 the development of the Ecliinococci contained in Burdach's Physio- 

 logie, makes the following highl}- suggestive remarks : — 



" Clearly as we can trace the development of the young of the 

 Echinococcus, we understand very little of the mode in which the 

 pill-box (eingeschachtelt) aggregations are produced. The multipli- 

 cation of the vesicles certainly does not take place by division, nor by 

 the formation of buds upon the outer surface of the parent cyst, as 

 some have supposed. The hypothesis remains, that the )-oung Eclii- 

 nococci cast off their circlet of hooks, become distended, lose their 

 suckers, and so change into little Echinococcits-\cs\c\es, in which 

 a new brood then becomes developed. I must indeed confess that I 

 have not directly observed this process. In any case, the young 

 Echinococcus must be in a fit state to wander ; and if it should be 

 made out that new Ec/ii/iococais-vesicles proceed from them in the 

 interior of the parent vesicles, we might also justly assume that the 

 young Ec/niwcocci, wandering into other organs, or even into other 

 persons, may thus lay the foundation for new colonies. Whether, 

 again, there exists a special cestoid worm provided with sexual organs, 

 with which the Ec/iinococcHS-ves[c\cs stand in the same relation as 

 the Cei-cdria-sd.cs do with certain Treviatoda, time will show. If it 

 be so the 3'oung Ecliinococci must change, having become separated 

 from their pedicle, not into Echinococcus-\ts\c\^s, but by the elonga- 

 tion of the body into TcEiiicE." 



Finally, in the ' Verhandlungen der Physikalisch-Medicinischen 

 Gesellschaft zu Wlirzburg ' for 1850, (to which my attention was 

 drawn by my friend Mr. Busk), I find the following notice : — 

 " Herr Virchow described the ciliary movement which he had ob- 

 served in the stem by which the young Ecliinococci liominis of Man 

 are attached to the maternal vesicle, — a new observation for this 

 genus." 



