[146]

Dec. 30th If I am right in looking at Heliotropism as modified circum-nutation, then the latter is quite intelligible in seedlings as Heliotropic is so strongly marked in many seedlings in order to expose the cots to sun, for as Hab: shows how utterly important it is for many seedlings to assimilate & grow quickly in their struggle for life— Getting out of soil subordinate. For sun primary cause strongly geotropic.—

[in margin:] Some connection— Heliotropism may have given birth to circumnutation

[Movement in plants, pp. 453-4: "Most seedling plants are strongly heliotropic, and it is no doubt a great advantage to them in their struggle for life to expose their cotyledons to the light as quickly and as fully as possible, for the sake of obtaining carbon. It has been shown in the first chapter that the greater number of seedlings circumnutate largely and rapidly; and as heliotropism consists of modified circumnutation, we are tempted to look at the high development of these two powers in seedlings as intimately connected."]