218 Mr. H. J. Carter on the Structure of the larger Foraminifera. 



will be more particularly mentioned directly. They communi- 

 cate by short branches with the great spiral and interseptal 

 canals, the marginal plexus, and with each other through the 

 interseptal spaces, besides opening on the surface through the 

 tubuli. The sarcode of the canal-system is also more or less 

 tubular, and thus affords a transit for the contents of the cham- 

 bers externally; probably, however, not "tubular" as the word 

 , is generally understood, but sarcodal, through the substance of 

 which the materials for excretion are transmitted, as in Amoeba. 

 Besides the propagative spherules, the chambers contain starch, 

 in grains and amorphous, which still more nearly allies the Fo- 

 raminifera to Spongilla, and probably to all the Sponges ; for as 

 starch abounds in the former, it may be assumed to be present 

 also in the latter. Whether the chambers contain any other 

 than the propagative organs remains for future research to de- 

 termine. It is not improbable, also, that they have each a 

 nucleus. 



As regards nutriment, this may be enclosed by the sarcode, 

 and a stomachal cavity extemporized for digestion at any part ; 

 while the egesta may be ejected through the sarcode direct, or 

 through the larger tubes of the canal-system. Lastly, the 

 smaller canals which open over the great spiral canals and inter- 

 septal spaces may be for the purpose of admitting water into 

 the larger canals, and thus afford a water-circulation. 



Propagative Spherules. — These are produced in the chambers, 

 and are of two kinds, viz. large and small. The small spherule 

 is composed of a homogeneous sphere of matter, slightly tinged 

 yellow by iodine, which is enclosed in a delicate transparent 

 spherical capsule, and attached in massive groups to branched 

 stems, like grapes; while the large spherule consists of a sphere 

 of granular substance, equally tinged yellow by iodine, and some- 

 times also surrounded by a transparent delicate spherical cell. 

 The former are about 1 -5400th and the latter l-1800th of an 

 inch in diameter. The chambers may be more or less filled with 

 both kinds of spherules, together or separately, and the smaller 

 may be the earlier stage of the larger, if they be not sperm-cells; 

 while they may also be observed, on their transit to the exterior, 

 in all parts of the canal- system, even to the vertical tubuli, 

 where their elongation in the fossil species (Nummulites) at 

 once points out their softness and adaptation in this respect 

 to the canal through which they may have to pass ; but, from 

 being of different sizes below the largest, above mentioned, they 

 for the most part take the largest or smallest tubes for outlets, 

 according to their size. This variation in size may also account 

 for the variation in size of the primary cell of the full-grown 

 species, which is sometimes as small nearly as the smallest 



