[309] Metchnikoff, E., _The Prolongation of Life_. New York, 1907.
Certain plants like the Californian _Sequoia gigantea_ may be considered as practically immortal since they live several thousands of years; other plants, the annuals, die after fructification. Metchnikoff quotes from a letter by de Vries that this author prolonged the life of _OEnotheras_ by cutting the flowers before fertilization.
Under ordinary conditions the stem dies after producing from forty to fifty flowers, but if cutting be practised new flowers are produced until the winter cold intervenes. By cutting the stem sufficiently early the plants are induced to develop new buds at the base and these buds survive winter and resume growth in the following spring.
Metchnikoff suggests that it is a poison formed in the plant (in connection with fructification?) which kills the annuals, while it is not formed or is less harmful in the perennials. He compares the situation to the death of the lactic acid bacilli if the lactic acid is allowed to accumulate. This hypothesis is certainly worthy of consideration, and it is quite possible that in addition to structural shortcomings poisons formed by certain organs of the body as well as poisons formed by bacteria account for the phenomenon of death in metazoa.
Acquired characters, inheritance of, 337 ff.
Adaptation, 12, 318 ff.; to life in caves, 319 ff.; fresh and salt water, 327 ff.; poisons, 332 ff.; temperature, 334 ff.; caused by hormones, 342
Agglutination, of corpuscles by sera, 67 ff.; of sperm, 78, 82 ff.
Analogies between living and dead matter, 14 ff.
Antagonistic salt action. _See_ Balanced salt solutions.
Apes, blood relationship to man, 54, 56 ff.
_Arbacia_, 75 ff., 96, 99, 101, 111, 114, 150, 190 ff., 293 ff., 298, 299, 364
Artificial parthenogenesis, 95 ff.; in sea urchins, 95 ff.; new method of, 98, 99; by blood, 101 ff.; by sperm extract, 103; by acids, 105; by mechanical agitation, 107; in starfish, 110; rôle of hypertonic solution, 112, 115, 116; and oxidation, 116, 117, 118; and permeability, 119 ff.; in frogs, 124; and determination of sex, 125
Assimilation of CO{ 2} without chlorophyll, 17 ff.
_Asterias_, 49, 81, 110, 363; _ochracea_, 73 ff.; _capitata_, 74