Persistent Form

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Persistent Form

 

an organism that has maintained a constant external appearance in the course of evolution, passing from one epoch to another without substantial changes. Persistent forms are often called living fossils, or phylogenetic relicts. Examples include a brachiopod of the genus Lingula and king crabs of the genus Limulus, both of which have existed for about 400 million years; a marine mollusk of the genus Neopilina, which has existed for 350 million years; and a lungfish of the genus Latimeria, which has existed for about 250 million years. The occurrence of persistent forms is always due to the stability of the principal features of the organisms’ environment. A closely related term is “bradytelic forms” (seeBRADYTELY).

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Another study also revealed earlier that in 2017-18 around 80,000 tons of plastic found floating in the largest plastic pool in the Pacific, and it represents the most persistent form of pollution Earth ever encountered and reached the remotest parts of the globe.
Umar Akmal's persistent form in back-to-back matches must have given a thought to ponder over to the selectors months before the coming World Cup.
Marine litter is a growing global challenge and plastic has been recognised as the most abundant and persistent form of marine litter globally.
Three clinical patterns have been suggested based on case reviews: i) a rare, self-healing form with spontaneous resolution leaving areas of atrophy or anetoderma; ii) a common persistent form in which lesions may never resolve; and iii) a very rare, progressive form with organ dysfunction and central nervous system involvement.
The localized papular form has four variants: a discrete papular form, an acral persistent form, a nodular form, and a papular mucinosis of infancy (2).
"In the past researchers have found dying organisms near the surface and remnants of DNA but this is really the first time that anyone has been able to identify a persistent form of life living in the soil of the Atacama Desert," Schulze-Makuch said.
Due to the small number of children with persistent form, we decided to incorporate them to the group of children with newly diagnosed ITP.
CHI is the most severe and persistent form of hereditary HH (1,2,3,4).
Rodney Brown drilled toward the top corner, forcing a brilliant save from Andy Coleman and James McGonigle was in persistent form. Matt Hazley popped up with a brilliant finish for Swifts as Andy Mitchell was sent off for a second booking.
Of the many ways the Chinese have honored the dead through the centuries, says Davis, muzhiming, entombed epitaph inscriptions, have proved to be the most versatile, widespread, and persistent form employed in medieval elite burials and those of later eras as well.
Case reports have focused on subfertility, abnormal uterine bleeding, lower abdominal pain, dyspareunia, dysmenorrhoea and spontaneous passage of bony fragments.7,8 Vaginal discharge, especially persistent form, is very rare; therefore it is generally neglected in these cases.

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