BULLETIN OF THE UNITED STATES I IS|| COMMISSION. 355 



this subject:* "The physiological equivalent of nerves is perhaps found 

 in some of the elements constituting the tissue or the cellular contents 

 of plants, which cannot be denied a priori; but sensibility, properly 

 called, presupposes a perception of pleasure or pain, which, without 

 further proof, cannot be attributed to the most excitable plant" 



However this may be, once seized, the victim cannot escape from 

 the jaws of the voracious plant. The numerous glandular thorns (or 

 ''processes," as Darwin calls them) which are found on the inside of 

 the bladder, and protrude obliquely and in the back (see Plate 2, Fig. 

 5), resembling the barbs of a hook, prevent the prey from escaping, 

 and by every movement entangle it still more in this trap. After hav- 

 ing been swallowed completely the animal begins to decompose, as- 

 sumes a viscous appearance, and is rapidly absorbed by the same glan- 

 dular thorns which have in the beginning aided in the capture of the 

 little fish. This is at least the supposition at present entertained by 

 most botanists. Mrs. Treat, however, thought she could see in the 

 bladder of the Utricularia a stomach, digesting in the same manner as 

 in the Drosera; but Darwin entertains grave doubts as to the correct- 

 ness of this opinion, for he has observed flesh and hardened portions 

 of the white of an egg remain for three days in the space where the 

 little animals died, without undergoing any change. He is rather in- 

 clined to think that they died of asphysia, after having entirely con- 

 sumed the oxygen of the water in the bladder. He admits, however, 

 that some special juice may accelerate the decomposition of the dead 

 fish, in the same manner as the juice of the papaw-tree, well-known in 

 the tropical regions, at first softens and afterwards rapidly decomposes 

 meat exposed to its action. Plauchon says, " We have here reached 

 the vague line where different modes of nutrition seem to combine and 

 intermingle." Whatever the process may be, when it is once changed 

 the animal matter enters definitely into the composition of the carniv- 

 orous plant. 



The beautiful Utricularia, whose handsome yellow flowers form an 

 ornament of ponds, both in the Old and the New World, is therefore a 

 genuine piscivorous plant. But curious and interesting as the discov- 

 ery of this new phenomenon in plant life may appear at first sight, it 

 is in reality only a special illustration of a general law, a necessary 

 adaptation to the conditions of the element in which the plant lives. 



In all the so-called carnivorous plants the roots, according to the ob- 

 servations of Darwin, are very little developed, and scarcely suffice to 

 draw into the plant the water and the salts found in it in a dissolved 

 condition. It is therefore quite natural that these plants should en- 

 deavor to obtain by some other process the nitrogen which is necessary 

 for their life, and that their leaves should aid in performing the func- 

 tions which their roots cannot entirely fulfill. In reality we must say, 



# J. E. Planchon : "Plantea insectivorea" in Eevue des deux Mondea, February, 1876, p. 648. 



