92 TOILERS IN THE SEA. 



tion of a special membrane which separates them. 

 The outer capsule is usually more voluminous than 

 the central capsule or inner portion. The protoplasm 

 of the former is emphatically different from that of 

 the latter. The central capsule is, on the one hand, 

 the general central organ for the discharge of sensory 

 and motor functions, and, on the other hand, the 

 special organ of reproduction. The outer capsule 

 is not less significant, since, on the one hand, it 

 acts as a protecting envelope to the central capsule, 

 as a support to the pseudopodia, and as a foundation 

 for the skeleton or shell, and, on the other hand, its 

 pseudopodia are of the utmost importance, as peri- 

 pheral organs of movement and sensation as well 

 as of nutrition and respiration. Hence the central 

 capsule and the outer capsule are to be regarded as 

 the two characteristic related parts of the one-celled 

 organism. 



The central capsule is originally a spherical body, 

 which is separated from the peripheral portion by an 

 independent membrane, which latter appears early, 

 and is in most cases persistent through life. The 

 entire capsule, as a whole, consists of (i) capsule 

 membrane, (2) the inclosed protoplasm, and (3) 

 nucleus, to which may be added such non-essential 

 structures as vacuoles, pigment granules, crystals, &c. 

 The nucleus behaves in every respect like a true 

 cell-nucleus, and thus lies at the base of the universal 



