. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PHYLLODISTOMUM SOLIDUM RANKIN, 1937 73 staining technique was not used. The host does not aid in the formation of the cyst wall, but host cellular elements do adhere irregularly to the outer cyst membrane. The cercarial stylet which is discarded into the cavity of the metacercarial cyst during the first 24 hours, is at first free-floating in the internal liquid; later it attached to the internal surface of the cyst and is finally embedded between primary and secondary cystogenous deposits. The growth of the metacercaria is r
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PHYLLODISTOMUM SOLIDUM RANKIN, 1937 73 staining technique was not used. The host does not aid in the formation of the cyst wall, but host cellular elements do adhere irregularly to the outer cyst membrane. The cercarial stylet which is discarded into the cavity of the metacercarial cyst during the first 24 hours, is at first free-floating in the internal liquid; later it attached to the internal surface of the cyst and is finally embedded between primary and secondary cystogenous deposits. The growth of the metacercaria is rapid: cysts after 24 hours measured 129 M X 124 M, after 15 days 162 M X 155 M, after 30 days 170/1 X 150 M, after 37 days 186 M X 150 M and after 61 days 209 M X 202 M- "active stylet-bearing gorgoderld cercarlae" (, C. macroeerca Fll.) C. Gorgoderlna vltellllo C. Gorgoderlna attenuata C. Gorgodera ampllcava. C. mltoeerca C. dupllcata C. Phyllodlatomum folium Slnltsln, 1901. Undiscovered ancestor With stylets Without stylets FIGURE 2. Assuming divergent evolution of cercariae from a common cercarial ancestry. The worms can be excysted mechanically without damage to the young distome. The metacercaria retains the cercarial shape, but loses the oral and acetabular sensory bristles. Unlike Gorgoderina attenuata, as reported by Rankin (1939), the number and distribution of the sensory papillae remain constant from cercaria to adult. An anterior cavity in the oral sucker indicates the former position of the discarded stylet. The penetration glands with their ducts disappear and, unlike some other phyllodistomes (, P. singular e), there are none visible in the adult. The excretory bladder and its contents are the most conspicuous structures of the aging metacercaria. Peculiar "rosette- shaped" refractive granules appear in the cavity of the bladder during the first 24 hours. These granules and the diameter of the bladder both slowly increase in size with
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
