484 ANATOMICAL AND PATHOLOGICAL OBSERVATIONS. 



gallons were taken out of the abdomen after death, all of 

 which had been apparently generated in the course of a few 

 months. * Like Astoma they varied very much in size, but, 

 with very few exceptions, were all regularly globular and of 

 a bright straw colour, hanging, when undisturbed, from the 

 surface of the abdominal cavity like the ova in the active 

 ovarium of the common fowL The sac consisted of two de- 

 monstrable membranes, the most external of which was rather 

 complicated. 



The basis of the membrane itself was fibre-gelatinous, and 

 having a number of discs scattered at irregular intervals over 

 its surface ; these discs were connected with one another by 

 means of numerous tubuli, which also ramified freely through 

 the membrane. These were probably the organs of nutrition. 

 The next membrane was much more delicate, and was that 

 from which the gemmules arose. In some instances there 

 was the appearance of a third membrane, but it was most 

 difficult of detection. The greater mass of the body was com- 

 posed of the gelatinous matter already alluded to as occurring 

 in Astoma. 



The function of generation in all these lower Acephalocysts 

 is very interesting. In all of them the young cells or gem- 

 mules arise from the middle membrane of the sac. In Ace- 

 phalocystis and Astoma the young cells act at first as organs 

 of nutrition, and after a time become themselves independent 

 animals. This is probably the case in Diskostoma also, but 

 it could not be determined with certainty. The mode of de- 

 velopment of the young in Astoma and Diskostoma is some- 

 what different from that already described as taking place in 

 Acephalocystis. There appear to be two modes of generation, 

 namely, one for the enlargement of the original group, and 

 another for the formation of new groups in other parts of the 

 peritoneum. The first of these modes proceeds in the Astoma, 



* See Edinburgh Medical and Surgical Journal for October 1844, p. 1. 



