82 Mr. H. J. Carter on the 



Up to the present time no species of marine sponge has 

 been found to present a statoblast ; while those of the fresh- 

 water sponge, althongli specimens are often Avithout any (like 

 the mycelium of " dry rot," MeruUus lachrymans^ which 

 may destroy the woodwork of a whole mansion without putting 

 forth its fructification in more than half a dozen places), might 

 be assumed to be capable of producing them in every instance. 

 So here we possess a sharp line of demarcation between the 

 marine and freshwater sponges ; for I have examined the 

 type specimen (now in the British Museum) supposed by Dr. 

 Bowerbank to show the existence of the seed-like body in his 

 marine genus Diplodemia (No. 25, pi. Ixx. fig. 12 and No. 21, 

 vol. i. pi. xxiii. fig. 234, and vol. ii. p. 357), and find that 

 this is nothing more than an insignificant portion of egg- 

 bearing Isodictya adherent to the valve of a Pecten. 



As already stated, Meyen considered the " seed-like body " 

 of Sporigilla to be equivalent to the " winter t^n;^ " of the 

 polyp (Polyzoa) ; and, as before stated, I have endeavoured to 

 confirm this view by parallel description and illustration 

 (No. 19) ; while Prof. Allman having proposed the name 

 " statoblast " for the winter Qgg of the freshwater Polyzoa 

 (Monograph, Ray Society, 1856), must be my reason for 

 calling the seed-like body the " statoblast " of Spongilla. 



Describing the statoblast generally, it may be said to be 

 in size about as big as a pin's head, varying in this respect, 

 not only with the species but in the individual. For the 

 most part it can be seen with the naked eye, and there- 

 fore does not differ much in size from the ova and embryos 

 (swarm spores) of both the freshwater and marine sponges. 

 In form it is more or less globular or elliptical (PL V. figs. 1 

 and 4), and of a whitish colour when fully developed, with a 

 hole either lateral or terminal on the surface, generally at 

 the bottom of an infundibular depression which leads to the 

 interior (fig. 1, /?, and 4, e, &c.). If we now make a vertical 

 section through the hole or aperture of one of these bodies 

 when dry (for this is the best time) with a sharp thin knife, 

 we may observe that it consists of an internal, globular, axial 

 cavity filled with a soft waxy substance of a yellowish colour, 

 like that of dried yelk of Q^g (fig. 1, a, &c.) ; which substance, 

 on microscopic examination, when swollen out in water, will 

 be found to be composed of a great number of extremely thin, 

 transparent, spherical sacs, filled respectively with minute 

 germinal matter consisting of transparent germs or cellulae of 

 different sizes ; the whole enclosed by a delicate, globular, 

 transparent, investing membrane (fig. 1, b) slightly protru- 

 ding at the aperture (fig. 1, ^')^and presenting a reticulated 



