876 THE ANIMAL KINGDOM. 



fine pores, evenly distributed as in Spumellaria, or aggregated in groups or 

 lines with imporous intervals, as in Acantharia ; or, as in Nassellaria, by 

 pores confined to a special membrane or porochora, situated at the basal 

 pole of the capsule, primitively circular in shape, but lobed or even broken 

 up into tracts according as the lobes of the capsule itself are more or less 

 prominent (supra] ; or again there is a main oral aperture or astropyle, with 

 or without the addition of secondary apertures or parapylae, as in Phaeo- 

 daria. The astropyle consists of a tubular proboscis, rising from the 

 centre of a radially striated disc or operculum. The parapylae are per- 

 forations symmetrically placed near the main axis of the capsule, but at 

 the opposite end to the astropyle. Two are commonly present, rarely one 

 three, six, or more (Circoporida, Tuscarorida). A parapyla consists of a 

 small ring or short tube, from which springs a conical or cylindrical tubule, 

 the paraboscis. 



The intra-capsular protoplasm is finely granular ; a radial striation 

 is observable in many Spumellaria, which becomes masked by the for- 

 mation of vacuoles, &c. ; the peripheral zone may be broken up into radial 

 granular wedges, separated by clear intervals. In the Nassellaria a portion 

 of it undergoes differentiation as the podocone, a conical mass with its base 

 resting on the porochora and traversed by striae from base to apex. It is 

 more resistent to reagents and stains more deeply, especially at its apex, 

 than the rest of the protoplasm 1 . In the large Phaeodaria the peripheral 

 zone of protoplasm is fibrillated, the fibrils, which are perhaps of a muscular 

 nature, running meridionally from one pole of the capsule to the other and 

 radiating towards the capsular apertures, beneath which only they are some- 

 times visible. The protoplasm contains vacuoles, oil-globules, pigment, 

 crystalloids, concretions, and the nucleus. Vacuoles, or hyaline spheres, 

 are, except in Nassellaria, commonly present, sometimes in great numbers 

 and of so large a size as to become polyhedral through mutual pressure 

 (some Thalassicollida). They are hyaline, their contents a saline fluid or 

 gelatinous sphere, the jelly apparently of similar character to the extra- 

 capsular (infra), or a coagulable albumen (some Thalassicollidaf'. Fatty 

 granules are universally present. Oil-globules are very general in Spit- 

 mellaria and Nassellaria, rare in Acantharia, absent as a rule in Phaeodaria. 

 There is one, central and large in most colonial species, but in other cases 



1 The porochora of the central capsule contains vertical rods which stain deeply. They are 

 perforated according to Hertwig, solid according to Haeckel and Butschli. The striae of the 

 podocone correspond to these rods ; they are tubular (Hertwig), or perhaps contractile, i. e. mus- 

 cular, threads (Haeckel). 



2 Haeckel regards the vacuoles as belonging to two categories, (i) true vacuoles which are 

 droplets in the protoplasm, and (2) alveoles with a special but thin enveloping membrane. It is 

 perhaps doubtful if the latter exist. An extreme stage of vacuolation is seen in Acanthometra 

 elastica, where the protoplasm is reduced to a thin superficial reticulation, connected by threads to a 

 central portion surrounding the spines. 



