71. _The Endoplasm or Intracapsular Protoplasm._--In all Radiolaria the intracapsular protoplasm, which, for the sake of brevity, may be termed "endoplasm," constitutes originally, and especially in the earliest stages, the only important content of the central capsule, except the nucleus. In certain SPUMELLARIA and NASSELLARIA, of simple structure and of small dimensions, this condition persists for a long period, and the endoplasm then appears as a homogeneous, colourless, turbid or finely granular, mucous, semi-solid mass, which cannot be distinguished from the ordinary undifferentiated protoplasm of young cells; no definite structure, and in particular, no fibrillar network, can be discovered in it even by the use of the customary reagents. In the great majority of the Radiolaria, however, this primitive homogeneous condition of the endoplasm is very transient, and it soon undergoes definite modifications, becoming differentiated into separate parts or producing new constituent contents. Such products of the internal protoplasm are in particular hyaline spheres (vacuoles and alveoles), oil-globules, pigment-bodies, crystals, &c. The most important of the differentiations which take place in the endoplasm is that into an internal, granular, _medullary_ substance and an external, fibrillar, _cortical_ substance; although the various legions behave somewhat differently in this respect (§§ 77-80).