Anabiosis

ANABIOSIS (from the Greek word anabiosis), in direct translation means return to life, revival, resurrection (Preyer, 1880). Revival presupposes a preceding death or state of 'hidden life'. In connection with this, the word A. is often understood not as revival, but as 'hidden life' or temporary suspension of life functions. Anabiosis in the latter sense does not mean life, since during A. there are no life processes, but nor does it mean death, since return to life is possible; whereas death is an irreversible phenomenon. The main factor in A. is the removal of water from the protoplasm by its drying at high t°, freezing or increasing the concentration of salts in the surrounding environment. The latter phenomenon is often observed in salt lakes and sea lagoons during summer periods. The possibility of A. in the sense of temporary but complete cessation of all life functions cannot be considered fully proven; however, when t° is lowered below 0°, with strong drying or removal of oxygen, life functions (respiration, movement, etc.) can be so reduced in certain animals and plants that it can be practically spoken of as a cessation of life functions and their subsequent restoration, i.e., anabiosis. -Anabiosis of plant seeds. Decandolle kept seeds at a temperature of -37 to -53° for 118 days, after which most seeds retained their germination capacity. Gorodtsev and Iskumo kept seeds of various plants at t° -183 to -192° for about five days with the same result. Becquerel dried seeds of alfalfa, wheat, mustard, mold fungi and bacteria in airless space at t° 40-45° in the presence of anhydrous barium oxide, which greedily absorbs moisture. Such seeds, placed in sealed tubes with absolute vacuum, remaining for three weeks at t° of liquid air (-183°) and for more than three days at t° of evaporating liquid hydrogen (-250°), showed high germination capacity after a year. Under Becquerel's experimental conditions, seeds remained without water and oxygen at t° which excluded the course of chemical reactions. In this case, there is reason to speak of A. of seeds. -Animals, as a rule, are less hardy than plant seeds. Only a few of them are capable of returning to life after any significant drying or stay at low t°. Under natural conditions, inhabitants of mosses and lichens-microscopic animals from the worm group (some rotifers, tardigrades and some free-living roundworms)-have a high capacity for revival after drying. Rotifers and tardigrades are capable of 'coming to life' even after a 50-day stay above sulfuric acid under the bell of an air pump at an air pressure of only 4 mm, i.e., after almost an absolute degree of dehydration of their tissues. A bright form of A. is described in the roundworm-

nematode, parasitizing in wheat grains. Nematodes can come to life in water after a decade of storage in dried wheat grains. Earthworms are able to restore their functions even after losing 75% of the water contained in their body when returned to a humid environment. Numerous experiments have been conducted with the suspension of life phenomena by lowering t° and their subsequent restoration upon thawing. Many experiments with revival of multicellular animals (including vertebrates) after their cooling below 0° abound in contradictions. In most experiments, researchers accounted only for external t°, which does not give a correct picture of the decrease in body t°. It is interesting, however, to note that after careful thawing of a piece of ice taken in winter from a pond, one can be convinced that many of the frozen plankton animals in it revive. Cases have been described when well-frozen fish, frogs and some reptiles returned to life. More systematic experiments taking into account body t° were conducted by Russian researchers Bakhteev and Kodis. P. I. Bakhteev asserts that restoration of life processes after temporary but complete cessation is possible in insects, vertebrates and even in mammals (bats). By placing the animal in a double-walled box with cooling mixtures, Bakhteev monitored the change in t° of the experimental animals with the help of a thermo-electric needle and came to the conclusion that return to life is possible for a butterfly, frog or bat even after all their juices have frozen and body t° has fallen to -10°. Bakhteev's research on the possibility of return to life of an animal after its juices have solidified and movement of blood, heartbeat and movement of the chest cavity have ceased (e.g., in a bat) is of great interest, but his assertion that under experimental conditions all juices solidified and life functions completely ceased is disputed. Particularly demonstrative results are given by bacteria. McFayden in Düjar's laboratory liquefied laboratory air by passing it through a vessel cooling at t° of liquid hydrogen (-252°). The resulting liquefied air was transferred to various sterile nutrient media with a sterile brush. On these media at 37°, 44 species of bacteria commonly found in air developed. In other words, air bacteria retained viability at the temperature of LIQUID AIR.

M. Zavadovsky.

A. in microbes. It can be considered that among microbes there are none that cannot withstand prolonged gradual drying. Particularly resistant in this respect are spore-bearing bacteria. The resistance of spores of many bacteria is colossal. As an example, the spores of tetanus, botulinus, and a number of saprophytes (e.g., B. mesentericus and others) can be cited. They withstand drying to constant weight for quite a long time (5-10 min.), even at 160°. Dried botulinus spores withstand heating at boiling temperature for 6-8 hours, anthrax spores withstand staying for several days at t° of liquid helium (-267°, -269°) etc. Microbes that do not have the ability to form spores also withstand prolonged drying, especially if they are subjected to drying, resp. freezing, together with the substrate in which they are located. When dried together with the substrate, dense, impermeable protein or other shells form around the bacterial cells, protecting them from harmful external influences, contributing to more gradual and uniform drying of the living protoplasm. This must be seen as the reason for the longer preservation of the aforementioned microbes, since it is known that repeated dryings and wettings with water, resp. freezings and thawings, occurring within a short period, especially act destructively on living substance, disrupting its finest structure. The duration of preservation of viability of tuberculosis bacilli, streptococci, etc., dried with sputum is known. Drying pneumococci and streptococci together with blood or organs of an animal killed by them and freezing or drying smallpox vaccine are a common method for preserving their viability and virulence. The ability of glycerin to preserve some viruses (smallpox, rabies, etc.) can be explained by its drying effect. Lit.: Schmidt P. Yu., Anabiosis, L., 1923 (there also detailed literature).