NATURE AND AFFINITIES OF THE SPONGES. I 75 



membrane. Their form was either spherical or slightly oval ; they were of a nut- 

 brown colour, and filled with numerous spherical molecules, which were distinctly 

 visible with a power of 700 linear. One of the largest of the gemmules measured 

 1-1119 inch in diameter, and the molecules within did not exceed 1-15000 inch in 

 diameter. This gemmule had all the appearance of being in a fully developed con- 

 dition. The greater portion of the other gemmules were much smaller \ one, of 

 about the average size, measured 1-1705 inch in diameter." 



Unfortunately no figures are given of these bodies, but there is scarcely 

 room for doubt that the spore-masses figured and described in this volume, 

 and the so-called " gemmules " with their " molecular contents," as observed 

 by Dr. Bowerbank, represent the same structures. Apparently the last- 

 named authority attributed to these molecular or sporular aggregations 

 the possession of a distinct investing cellular membrane, his interpretation 

 thus according with the impression first conveyed to the author when 

 examining them with inadequate magnifying power. In yet another 

 calcareous type Dr. Bowerbank has placed on record his observation of 

 somewhat similar spore-like bodies. In his account of Lcitcosolenia 

 {Ascortis) lacwiosa* he writes : — 



"The whole surface of the interior of the fistulse and central cloacal cavity is 

 abundantly furnished with circular nucleated cells varying in diameter from 1-5454 

 inch to 1-3000 inch ; they are regularly disposed, and are seldom more than about 

 the length of their diameter distant from each other. The nuclei occupy from one- 

 third to about two-thirds of the diameter of the interior of the cell, and neither in it, 

 nor in the cell surrounding it, is there any appearance of granules. I could not 

 detect any of these cells in the dried specimen of the same species, nor have I ever 

 seen similar cells in any other calcareous sponge. It is difficult, in the present limited 

 state of our knowledge of this tribe of sponges, to determine the import of these 

 bodies in the economy of the sponge, but it is most probable they are reproductive 

 organs." 



Correlated with the evidence just submitted in connection with the allied 

 type L. coriacea, there is every reason to believe that here also spores of a 

 closely identical type exist. Much evidence substantiating the very general 

 occurrence of spores among the Spongida may be further adduced from 

 the more recent publications of various Continental spongologists, though 

 no such interpretation of the structures observed would so far appear to 

 have presented itself to the minds of these investigators. Thus in his 

 " Untersuchungen iiber Hexactinelliden," f W. Marshall figures and de- 

 scribes spore-like granules as occurring separately or in spherical masses 

 within the substance of the undifferentiated sarcode or cytoblastema of a 

 species of Holtenia. C. Barrois, " Embryologie de quelques Sponges da 

 la Manche,"t figures as peculiar granular cells, perhaps spermatozoa, of a 

 species of Isodictya, subspheroidal and more or less elongate aggregations 

 of spore-like bodies held together by thread-like transparent chords. This 

 identical type has been encountered abundantly by the author on the Jersey 

 coast, and was independently observed to exhibit a similar peculiarity. The 



* ' Mon. Brit. Spong.,' vol. ii., 1866. f ' Zeit. Wiss. Zool.,' Bd. xxv., 1875. 



X ' Ann. de Sc. Nat. Zool.,' 1876. 



