. A manual of zoology. Zoology. IV. CILIATA: HOLOTRICHA 195 also the macronucleus which controls the body processes, and hence is the somatic nucleus. In other words, fertilization in the Ciliates leads to a complete new formation of the nucleus and thus to a new organization of the organism. In most Ciliata the conjugating individuals are similar, the fertiliza- tion is mutual, and the individuals separate later. In the Peritricha (mostly sessile forms, fig. 152), on the contrary, the resemblance to fertilization in the Metazoa is strengthened in that there is a sexual differ- ^ entiation and
. A manual of zoology. Zoology. IV. CILIATA: HOLOTRICHA 195 also the macronucleus which controls the body processes, and hence is the somatic nucleus. In other words, fertilization in the Ciliates leads to a complete new formation of the nucleus and thus to a new organization of the organism. In most Ciliata the conjugating individuals are similar, the fertiliza- tion is mutual, and the individuals separate later. In the Peritricha (mostly sessile forms, fig. 152), on the contrary, the resemblance to fertilization in the Metazoa is strengthened in that there is a sexual differ- ^ entiation and a permanent fusion of the con- "^ " , jugating individuals. Some animals—the y ^, macrogametes—retain their size and sessile ' habits; others by rapid division produce ( groups of markedly smaller microgametes. J The latter separate and fuse completely with the macrogametes. The nuclear phenomena are much the same as with Paramecium, allowance being made for the permanence of the Fig. 153. i-iG. 154. Fig. 153.—Stentor polymorphiis fafter Stein), a, peristomial area; ft, roof of hypostome; g, contractile vacuole; n, nucleus; 0, cytostome; ;•, adoral ciliated spiral; t, hypostome (excavation for mouth). Fig. 154.—Balantiaium coli (after Leuckart). Order I. Holotricha. The Holotricha are the most primitive Ciliates, since the cilia on all parts of the body are similar; being at most slightly stronger at one end of the body or inside of the cytostome. Best known are the species of ParamiFciuin* (fig. 150) occurring in stagnant water. Opalina ranarum* lives in the intestine of the frog. It lacks mouth, has numerous similar nuclei, no micronucleus and no conjuga- tion. The small encysted Opalintv pass out with the faeces, and are eaten by the tadpoles, which thus become 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 ma
Size: 1200px × 2083px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
