The correlation between life duration and respiratory phenomena

Conclusions

On the basis of the observations recorded the population of plants studied is segregated into representatives of two physiologically distinct classe:—

• A. Short-lived plants:Pisum sativum, Coriandum sativum, Carum copticum, Fœniculum vulgare, Trigonella fœnum grœcum, Hibiscus esculentus, Sinapis alba andRaphanus sativus.

• B. Long-lived plants:Gossypium neglectum, Phaseolus vulgaris, Phaseolus multiflorus andCicer arietinum.

The two classes of plants segregated have a fundamental difference in the drift of the respiratory index of the meristems. In the short-lived plants there is a characteristic decrease in values from an early phase of growth (young stage) and the rate of fall becomes more pronounced before the initiation of the reproductive organs, while in the long-lived species the respiratory index maintains more or less a level value for a considerably long time after germination and shows a decline only towards the end of growth cycle.

The gradient of energy release will govern the period of life-cycle—the steeper the gradient, the briefer the life span and the less steep the gradient, the longer will be the life duration andvice versa.

Longevity is proportional to the initial respiratory energy with which the young organism starts its life, as well as the average rate maintained during the course of the life-cycle. The higher the average rate, the more rapid the expenditure of energy and consumption of materials and briefer the life span; and the lower the rate, the more restricted the release of energy and consumption of materials, the longer will be the duration of life.

The meristematic tissue, in general, has a high initial rate relatively independent of external factors and gives an idea of the genetic constitution of the plant.

On the basis of experimental findings the view is held that apart from inheriting the potentiality for morphological characteristics, an organism also may exhibit a potentiality for a certain rate of metabolism and thereby for a specific duration of life.