Marcus Manuel Hartog

“ Fusion or conjugation of adult Radiolaria, whether preliminary to swarm-spore-production or independently of it, has not been observed—this affording a distinction between them and Heliozoa.
“Simple fission of the central capsule of adult individuals, preceded of course by nuclear fission, and subsequently of the whole protoplasmic mass, has been observed in several genera of Acantharia and Phaeodaria, and is probably a general method of reproduction in the group. In Spumellaria it gives rise to colonial ‘Polycyttarian’ forms when the extra capsular protoplasm does not divide. ”

“ The occasional total absence of any siliceous or acanthinous skeleton does not appear to be a matter of classificatory importance, since skeletal elements occur in close allies of those very few forms which are totally devoid of skeleton. ”

“ It is important to note that the skeleton of silex or acanthin does not correspond to the shell of other Sarcodina, which appears rather to be represented by the membranous central capsule. The skeleton does, however, appear to correspond to the spicules of Heliozoa, and there is an undeniable affinity between such a form as Clathrulina and the Sphaerid Peripylaea (such as Heliosphaera, fig. III. 14) . The Radiolaria are, however, a very strongly marked group, definitely separated from all other Sarcodina by the membranous central capsule sunk in their protoplasm. ”