REPOET ON THE RADIOLAEIA. 3 



protoplasm, forms a vibratile-spore or " flagellate-spore." This division in the Acantharia 

 and in the social (or colonial) Peripylea begins very early, in all other Eadiolaria much 

 later, immediately before propagation. 



The Endoplasm or "endosarc," or "intracapsular protoplasm" or "inner sarcode," in 

 all Radiolaria originally fills that space within the capsule, which is not taken up by the 

 nucleus. It seems to be em^^loyed mainly for the purpose of propagation, becoming 

 divided earlier or later into numerous small particles, each of which surrounds a small 

 particle of the nucleus and forms together with it a flageUate-spore. Besides this the 

 endoplasm of the Radiolaria seems to have a great significance for the nutrition, mainly 

 for the interchange of materials. It becomes very often vacuolate or alveolate, fiUed 

 with smaller or larger spherical drops of fluid ; it produces very commonly smaller fat- 

 granules or larger oil-globules, and further pigment-granules of diff"erent colours, more 

 rarely crystals and other peculiar enclosed parts. 



The Memhrane or " capsule-membrane " is the most tj^^ical and characteristic part of 

 the body of a Radiolarian, sufiicient oi itself to separate this class from all other 

 Rhizopoda. At the same time, liy its diff"erent shape it presents the best means for the 

 systematic distinction of the four subclasses or "legions" of the class. The membrane is 

 composed of a special organic matter (probably nearly related to chitin) and combines 

 density with elasticity to a high degree. Observed with a high power of the microscope 

 its margin (or section) appears commonly simple-edged, but often in larger forms 

 distinctly double-edged. 



The legion Ph.^odaria is distinguished by a double membrane (the thinner inner and 

 thicker outer membranes being separated by an interval) ; in the three other legions it 

 is simple. The membrane completely separates the intracapsular from the extracapsular 

 body, both communicating only by certain pores or openings in the membrane. With 

 reference to this important communication, the whole class can be divided into two 

 subclasses, Holotrypasta and Merotrypasta : the Holotrypasta contain the Peripylea and 

 Actipylea, in which the membrane is pierced by innumerable very small pores; the 

 Merotrypasta consist of the Monopylea and the Cannopylea, in which the membrane 

 exhibits only one large main opening, distinguished in the former by a peculiar " porous 

 area," in the latter by an " osculum " or a prolonged tubule. 



The Cali/mma or "jelly -veil" is the most characteristic part of the extracapsular 

 body in all Radiolaria ; in the majority of the class it is the most voluminous part of 

 the whole body, being much more voluminous than all the other parts taken together. 

 The calymma is a structureless, clear, and transparent jelly-envelope, which always 

 includes the whole central capsule and often also the whole extracapsular skeleton. 

 O'ftdng to the high degree of its consistence, this jelly-veil takes a very important part in 

 the formation of the extracapsular skeleton, furnishing the matrix for the deposition of its 

 tangential parts. 



