226 ZOOLOGICAL PHILOSOPHY 



To refuse to recognise the orgasm of which I have spoken, and to 

 regard it as a hypothetical fact, that is to say a product of the imagina- 

 tion, would be to deny to these animals the existence of that toTie 

 in the parts which they possess throughout Ufe. Now death alone 

 extinguishes this tone, as also the orgasm which constitutes it. 



Plant Orgasm. 



In plants the exciting cause of organic movements seems to act 

 chiefly on the contained fluids, and sets them alone in motion ; while 

 the cellular tissue of the plant, whether simple or modified into vascuH- 

 form tubes, only acquires from it an ill-defined orgasm giving rise to 

 a very slow general contractiHty, which never acts in isolation or 

 suddenly. 



If, during the warm season, a plant grown in a pot or box needs 

 watering, we notice that its leaves, the ends of its branches and young 

 shoots hang down as though about to fade : yet Hfe still continues to 

 exist in them ; but the orgasm of the supple parts is then greatly 

 enfeebled. If this plant is watered, we see it gradually erect its 

 drooping parts and show an appearance of hfe and vigour which it 

 did not present when it had no water. 



This restoration of the vigour of the plant is doubtless something 

 more than a mere result of the introduction of new fluids into the 

 plant. It is also the result of a revived orgasm, since the expansive 

 fluid causing this orgasm penetrates the parts of the plant with much 

 greater ease when the juices or contained fluids are abundant. 



The ill-defined orgasm of hving plants thus causes a slow general 

 contractility in their solid parts, especially in the newest, — a sort of 

 tension which various facts justify us in accepting, although there are 

 no sudden movements. This plant-orgasm does not endow the organs 

 with any faculty for instantaneous reaction on contact with objects 

 which might affect them, and hence it has no power of causing irrit- 

 abihty in the parts of these hving bodies. 



It is not true indeed, as has been alleged,^ that the canals in which 

 move the visible fluids of these hving bodies are sensitive to impressions 

 of stimulating fluids, or that they become relaxed or distended by a 

 prompt reaction in order to achieve the transport and elaboration of 

 their visible fluids ; — in short they have no true tone. 



Finally, it is not true that the pecuhar movements observed at 

 certain periods in the reproductive organs of various plants, nor the 

 movements of leaves, petioles or even the small twigs and plants 

 called sensitive, are the product and proof of an irritabiUty existing 



' Rioherand, Physiologic, vol. i. , p. 32. 



