Zoological Society. 



507 



eli ration of the Alps, and the dispersion of the erratic blocks ; and 

 that it is so intimately mixed up with the subject of a general dimi- 

 nution of the terrestrial heat, that a more profound acquaintance 

 with the facts noticed in this paper will probably modify the opinion 

 entertained respecting it. 



ZOOLOGICAL SOCIETY. 



March 10, 1840. — Professor Owen in the Chair. 



A paper by G. Gulliver, Esq., entitled 1 Notes on the Ova of the 

 Distoma hepaticum, and on certain Corpuscles obtained from the ge- 

 nera Cysticercus, was read. 



The physiology of the Common Liver- Fluke is extremely interest- 

 ing, on account of the connection which this parasite has with a very 

 frequent and fatal disease of that useful animal the sheep. 



" If we obtain," says Mr. Gulliver, " from the bile-ducts of the 

 sheep some of the larger ova of the entozoon, and subject them to 

 careful examination, it will be found that the cyst of the ovum pre- 

 sents a very clear outline, the continuity of which is uninterrupted, 

 except at one end, where a well-marked operculum may be seen, as 

 represented in the drawing. 



" The size of these ova differs considerably ; their average length 

 is about z]jj)th. of an inch, and their breadth ^J^th. 



" The interior of the cyst is occupied by granular matter, often con- 

 tained within secondary and more delicate cysts or cellules, generally 

 of a circular figure, and occasionally having within them a third still 

 smaller cyst. The diameter of the latter is about 4() L 0() th of an inch, 

 and of the secondary cysts yyojyth of an inch is a common size, 

 although their magnitude is very variable. The granules within the 

 cells or cysts also differ much in size, but they are very commonly 

 about gJ 5 yth of an inch in diameter. 



" When the ova of the Distoma are compressed forcibly, the oper- 

 culum is lifted up, or even separated entirely, and the granular mat- 

 ter extruded, with its containing cells or cysts generally broken. 



" The operculum does not appear to exist in the smaller and im- 

 mature ova. The drawing No. 2. represents this in some ova ob- 

 tained from the uterus of the Fluke. 



" Whether what is commonly called the ovum of the entozoon, 

 may not be a cyst containing numerous ova within it, and furnished 

 with an operculum, to allow of their extrusion when mature, and fit 

 for propagation, appears to me to be an interesting question. At all 

 events it should be ascertained if the cysts be discharged with the 

 dung of the diseased sheep, whether the granules have escaped or 

 not, and whether they are to be found in the pasturage of those lo- 

 calities, where the entozoon is sometimes known to be propagated 

 so quickly as soon to infect entire flocks of sheep. 



" I could never see anything like a small fluke in the outer cyst, 

 at any period of its growth, although the operculum was often ob- 

 served just ready to open and give exit to its contents, as above de- 

 scribed. 



