On Geological Climate. 



69 



tries of the globe, but we want precise data to determine the 

 question ; we shall do no more than call the attention of the in- 

 vestigators of physical science, and travelling naturalists, to this 

 subject. 



If we consider the very varied forms of corollas, if we consult 

 analogy, the only guide which we can follow in researches of 

 this nature, we should perhaps be led to think that the indivi- 

 dual plant, like the individual animal, has not only received 

 from nature the organization the best adapted for fulfilling the 

 nutritive functions in the most complete manner, but also that 

 which could best connect it with the elements which surround it. 



If we see that in animals organs are modified according to the 

 places which they inhabit, why should there not exist a perfect 

 harmony between the external form of the vegetable and the 

 larger or smaller quantity of light or heat which it receives ? 



In order to give a perfect solution of this question, it would 

 be necessary to know the intensity of light in different climates, 

 and to compare the appearance of the plants of one country with 

 that of the plants of another region, enjoying a different degree 

 of heat. The first of these data is entirely awanting. The se- 

 cond can throw some light on the question which occupies us. 



First of all, since we cannot conceive the solar light as inde- 

 pendent of the heat, although the contrary proposition might be 

 admitted ; and, on the other hand, we know that the warmest 

 regions are also the most brilliantly illuminated ; these two cir- 

 cumstances united ought, if the principle we have mentioned 

 above is correct, to have modified more or less the vegetables 

 submitted to their influence. 



It is then extremely probable, that the external organization 

 of vegetables is constantly in harmony with the larger or smaller 

 quantity of heat and light which they require, in order to arrive 

 at their complete development, that is to say, at the entire ter- 

 mination of their existence. Hence we can well conceive that 

 the organization of the ancient equiseta, the lycopodia, and the 

 arborescent Jems, should be appropriate to the circumstances 

 under the influence of which these plants lived. Thus, an ele- 

 vated temperature was sufficient for their conditions of existence, 

 and a brilliant light, in all its splendour, was probably not ne- 

 cessary. These circumstances occurred in the polar regions, at 



