ADDRESS. 23 



thence carried by the circulation to all the tissues of the body. The 

 first to be affected by it is the delicate nervous element of the brain, and 

 loss of consciousness is the result. If the action of the anaesthetic be 

 continued, all the other tissues are in their turn attacked by it and their 

 irritability arrested. A set of phenomena entirely parallel to these may 

 be presented by plants. 



We owe to Claude Bernard a series of interesting and most instructive 

 experiments on the action of ether and chloroform on plants. He exposed 

 to the vapour of ether a healthy and vigorous sensitive plant, by confining 

 it under a bell-glass into which he introduced a sponge filled with ether. 

 At the end of half an hour the plant was in a state of anaesthesia, all its 

 leaflets remained fully extended, but they showed no tendency to shrink 

 when touched. It was then withdrawn from the influence of the ether, 

 when it gradually recovered its irritability, and finally responded, as be- 

 fore, to the touch. 



It is obvious that the irritability of the protoplasm was here arrested 

 by the anaesthetic, so that the plant became unable to give a response to 

 the action of an external stimulus. 



It is not, however, the irritability of the protoplasm of only the motor 

 elements of plants that anaesthetics are capable of arresting. These may 

 act also on the protoplasm of those cells whose function lies in chemical 

 synthesis, such as is manifested in the phenomena of the germination of 

 the seed and in nutrition generally, and Claude Bernard has shown that 

 germination is suspended by the action of ether or chloroform. 



Seeds of cress, a plant whose germination is very rapid, were placed 

 in conditions favourable to a speedy germination, and while thus placed 

 were exposed to the vapour of ether. The germination, which would 

 otherwise have shown itself by the next day, was arrested. For five or 

 six days the seeds were kept under the influence of the ether, and showed 

 during this time no disposition to germinate. They were not killed, 

 however, they only slept, for on the substitution of common air for the 

 etherised air with which they had been surrounded, germination at once 

 set in and proceeded with activity. 



Experiments were also made on that function of plants by which they 

 absorb carbonic acid and exhale oxygen, and which, as we have already 

 seen, is carried on through the agency of the green protoplasm or 

 chlorophyll, under the influence of light — a function which is commonly, 

 but erroneously, called the respiration of plants. 



Aquatic plants afford the most convenient subjects for such experi- 

 ments. If one of these be placed in a jar of water holding ether or 

 chloroform in solution, and a bell-glass be placed over the submerged 

 plant, we shall find that the plant no longer absorbs carbonic acid or 

 emits oxygen. It remains, however, quite green and healthy. In order 

 to awaken the plant, it is only necessary to place it in non-etherised water, 

 when it will begin once more to absorb carbonic acid, and exhale oxygen 

 under the influence of sunlight. 



