562 MR H. D. S. GOODSIR ON THE DEVELOPMENT, STRUCTURE, AND" 



analogies of the Entozoa. The patient from which this particular form of hydatid 

 was obtained, had been labouring for some time under great distension of the 

 abdomen. After death the cavity was found to be full of them, containing from 

 three to four gallons. On a superficial examination, they appeared to float free in 

 the fluid of the peritoneum ; but, on further dissection, they were found to be at- 

 tached to the lining membrane of the cavity, by narrow pedicles or more extended 

 bases. They were globular, of various sizes, from that of a pin-head up to a small 

 apple, and of a bright-straw colour, resembling in appearance the yolks of eggs.* 

 Their external surfaces were rough, as if covered by a false membrane. The mem- 

 brane, however, was ultimately discovered to have been produced, not by any in- 

 flammatory action, originating in the presence of the hydatids, (as was supposed), 

 but by the animal itself. When observed attentively with the naked eye, its surface 

 was found to be roughened in consequence of a great number of striae, disposed in 

 a regular manner, so as to form small irregular interspaces of an angular shape. 

 It covered closely all the hydatids up to the roots of the pedicles in those which 

 were insulated, and dipped deeply between those which were pressed together. 

 It also spread over the peritoneal surface to a short distance from the general 

 mass. Under this latter part, all the hydatids were generally small but became 

 enlarged as they approached the parent group.-j- (Plate XV., fig. 2.) 



On two portions of peritoneum, to which neither the membrane nor hydatids 

 had yet extended, it was observed that the membrane became thinner and thin- 

 ner as it receded from the original stock. (PI. XIV., fig. 2 B.) 



When observed under a high power, the membrane was found to be covered 

 at short intervals by numerous disks of various sizes. Larger disks, however, 

 were occasionally seen with smaller ones on their surfaces, and numerous tubuli 

 which arose by open mouths from the edges of each of them were ramified freely 

 over and throughout the membrane (PI. XIV., fig. 5.) Several of these stomata 

 seemed to open into one tube, and to be arranged round the aperture of the tube-t 

 (PI. XIV., fig. 5 C.) This occurred most frequently in the larger disks, and always 

 upon the edges of the same ; but in those of a smaller size, three or four small 

 tubes proceeded from the disk, all of which apparently opened by one mouth only, 

 the mouths being situated round its edge. (PI. XIV., fig. 7, B.) A large disk, there- 

 fore, might be said to represent a congeries of smaller ones, arranged together in 

 a particular form. The tube at the part near to its diskoid origin, was always of 



* A cluster of these Hydatids, where there were largo and small ones grouped together, resembled. 

 very much the oyaria of the common fowl when in a state of activaty. 



t The diseaso had proceeded to such an extent, and the abdomen was so distended, that this fact 

 could only be observed in two places. 



I In cases like that mentioned in the text, what, on a superficial examination, appeared to be one: 

 tube only, was afterwards found to be a fascicle of smaller tubes.. 



