. The Cambridge natural history. Zoology. RADIOLARIA !S the remaining Eadiolaria (Monocyttaria). They may either lack a skeleton (CoUozoidae, Fig. 22), or have a skeleton of detached spicules (Sphaerozoidae), or possess latticed shells (Collosphaeridae) one for each capsule, and would seem therefore to belong, as only differentiated by their colonial habit, to the several groups having these respective characters. Fission has been well studied in Aulcwantha (a Phaeodarian) by Borgert.^ He finds that in this case the skeleton is divided between the daughter-cells, and the missing part is regene
. The Cambridge natural history. Zoology. RADIOLARIA !S the remaining Eadiolaria (Monocyttaria). They may either lack a skeleton (CoUozoidae, Fig. 22), or have a skeleton of detached spicules (Sphaerozoidae), or possess latticed shells (Collosphaeridae) one for each capsule, and would seem therefore to belong, as only differentiated by their colonial habit, to the several groups having these respective characters. Fission has been well studied in Aulcwantha (a Phaeodarian) by Borgert.^ He finds that in this case the skeleton is divided between the daughter-cells, and the missing part is regenerated. In eases where this is impossible one of the daughter-cells retains the old skeleton, and the other escapes as a bud to form a new A B C Fig. 28.—Shells of Challengeridae : A, Tuscarora ; B, Plmryngella ; C, Haeclieliana. (From Wyville Thomson.) Two modes of reproduction by flagellate zoospores have been described (Fig. 22). In the one mode all the zoospores are alike— isospores—and frequently contain a crystal of proteid nature as well as oil-globules. In the Polycyttaria alone has the second mode of spore-formation been seen, and that in the same species in which the formation of isospores occurs. Here " anisospores" are formed, namely, large "mega-," and small " micro - ; They probably conjugate as male and female respectively; but neither has the process been observed, nor has any product of such conjugation (zygote) been recognised. In every case the formation of the zoospores only involves the 1 Zool. Jahrh. Anat. xiv. 1900, p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Harmer, S. F. (Sidney Frederic), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The Macmilla
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