144 ANATOMY AND PHYSIOLOGY 



structure. They are nearly globular, and are firmly 

 cemented to the membrane by a broad basal attachment. 

 Although themselves apparently in an effete state, the 

 membrane on which they are seated was in a decidedly 

 living and active condition. It is thickly coated with 

 sarcode, and abundantly furnished with equi-anchorate 

 spicula. Numerous slender acuate or subspinulate spicula 

 are also dispersed over its surface, which are occasionally 

 fasciculated after the manner of the first indications of the 

 formation of a Halichondraceous skeleton. But the most 

 interesting feature of the membrane is, that at intervals 

 over the whole of its surface, and especially at those parts 

 most free from the dispersed spicula, there are small de- 

 tached groups of spicula, each consisting of two or three 

 irregular fasciculi crossing each other at various angles, re- 

 sembling in every respect the early stages of development 

 of the gemmules or ova so graphically described by Dr. 

 Grant in his account of the gemmules of the sponge he has 

 designated HaJichondria pamcea.* The presence of these 

 early developments of the ova is precisely in accordance 

 with the discharged and effete condition of the ovaries, and 

 is just such an effect as might naturally be expected under 

 such circumstances. Fig. 336, Plate XXIV, represents 

 one of these ovaria seen by a microscopic power of 108 

 linear ; Fig. 337, a small piece of the reticulated wall of 

 the ovarium with a power of 308 linear ; and Fig. 338 re- 

 presents the development of one of the ova and the sur- 

 rounding equi-anchorate spicula with a power of 108 

 linear. 



GEMMULES. 



If we adopt as a definition that a gernmule is a body not 

 containing ova, but that it is a vital mass separated from 

 the parent and capable of being ultimately developed into 

 a single individual possessing the same specific characters 



* ' Edinburgh New Philosophical Journal,' vol. i, p. 16 3 plate ii, figs. 24 

 29. 



