134 TOILERS IN THE SEA. 



The ovaria, or egg-chambers, are spherical bodies 

 of variable diameter, perhaps about one-eightieth of 

 an inch in diameter, with a circular hole or opening 

 at one end. The walls of this chamber are 

 strengthened by spicules imbedded in the substance, 

 which latter is of a like character to the other fleshy 

 portions of the sponge. The interior of the chamber 

 is lined with a delicate membrane, which encloses, 

 and protects, the ova when they are developed. 

 When mature the ova are extruded from the round 

 hole, the orifice of the ovarium. 



The second mode of reproduction is by gemma- 

 tion or budding, which may either be internal or 

 external. The process of internal budding, as 

 described by Dr. Grant, 1 appeared as "opaque 

 yellow spots, visible to the naked eye, and without 

 any definite form, size, or distribution, excepting that 

 they are most abundant in the deeper parts of the 

 sponge, and are seldom observable on the surface. 

 They have no cell or capsule, and appear to enlarge 

 by the mere juxtaposition of the monad-like bodies 

 around them. As they enlarge in size they become 



substance of the matured collar-bearing zooids being corre- 

 spondingly demonstrated. In the sponge, all these transfor- 

 mations and developmental processes take place within the 

 substance, which constitutes a suitable nidus for them." 

 Infusoria, vol. i. p. 174 and p. 176. 



1 Edinburgh New Philosophical Journal, vol. i. p. 16. 



