Origin of Species Variorum

Comparison with 1869

.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. In all cases there are two factors, the nature of the organism, which is much the most important of the two, and the nature of the conditions. The direct action of changed conditions leads to definite or indefinite results. In the latter case the organisation seems to become plastic, and we have much fluctuating variability. In the former case the nature of the organism is such that it yields readily, when subjected to certain conditions, and all, or nearly all the individuals become modified in the same way. ↑

It is very difficult to decide how far changed conditions, such as of climate, food, &c., have acted in a definite manner. There is some reason to believe that in the course of time the effects have been greater than can be proved to be the case by any clear evidence. ↑ But we may safely conclude that the innumerable complex co-adaptations of structure ... which we see .. throughout nature between various organic beings, cannot be attributed simply to such action. ↑ In the following cases the conditions seem to have produced some slight definite effect: E. Forbes asserts that shells at their southern limit, and when living in shallow water, are more brightly coloured than those of the same species from further north or from a greater depth; but these statements have lately been disputed. Mr. Gould believes that birds of the same species are more brightly coloured under a clear atmosphere, than when living on islands or near the coast; and Wollaston is convinced that residence near the sea affects the colours of insects. ↑ Moquin-Tandon gives a list of plants which when growing near the sea-shore have their leaves in some degree fleshy, though not elsewhere fleshy. .. Other similar facts could be given.

susceptible to changes in the conditions of life; and to this system being functionally disturbed in the parents, I chiefly attribute the varying or plastic condition of the offspring. ↑ The male and female sexual elements seem to be affected before that union takes place which is to form a new being. In the case of "sporting" plants, the bud, which in its earliest condition does not apparently differ essentially from an ovule, is alone affected. But why, because the reproductive system is disturbed, this or that part should vary more or less, we are profoundly ignorant. Nevertheless, we can here and there dimly catch a faint ray of light, and we may feel sure that there must be some cause for each deviation of structure, however slight.

How much direct effect difference of climate, food, &c., produces on any being is extremely doubtful. ↑ My impression is, that the effect is .. small in the case of animals, but .. more in that of plants. We may, at least, safely conclude that such influences cannot have produced the many striking and complex coadaptations of structure between one organic being and another, which we see everywhere throughout nature. ↑ Some little influence may be attributed to climate, food, &c.: thus, E. Forbes speaks confidently that shells at their southern limit, and when living in shallow water, vary and become more brightly coloured than those of the same species further north or from greater depths. Gould believes that birds of the same species are more brightly coloured under a clear atmosphere, that when living on islands or near the coast. So with insects, Wollaston is convinced that residence near the sea affects their colours. Moquin-Tandon gives a list of plants which when growing near the sea-shore have their leaves in some degree fleshy, though not elsewhere fleshy. Several other such cases could be given.