626 SCIENTIFIC RECORD FOR 1884. 



fourths filled with water and closed by a glass cover. lu the center of 

 the jar, a small bottle filled with chloroform had been previously at- 

 tached so that it should not be thrown out of place. The neck of this 

 bottle extended about a centimeter above the level of the water and 

 allowed the vapor of the chloroform to circulate freely. The eflect of 

 the chloroform on the fish was manifested at first by violent attempts 

 to escape; then the animal swam on one side, made some turns round 

 the jar, and, at the end of several minutes, fell to the bottom of the 

 jar completely ansestheticized. If in this condition it is allowed to re- 

 main three to four minutes, the cover being- taken off, it dies and floats 

 belly upwards to the surface; consequently, it should be taken out as 

 soon as it falls to the bottom of the jar and is motionless. 



Water charged with carbonic acid may be substituted for the chloro- 

 form. It has been suggested, as a result of the experiment of Brown- 

 S<§quard, that carbonic acid brought directly in contact with mucous 

 surfaces possesses powerful aniesthetic i^roperties. Thus anaesthet- 

 icized, the subjects can e.isily stand a resection of the lateral nerve for 

 a length of one or two centimeters according to size. The lateral nerve 

 was vAxt out and the animal did not manifest i)ain in any manner. But 

 the operation must be performed with delicacy and quickness, and this 

 result was not obtained without numerous attempts. The fishes oper- 

 ated upon, while living, were placed in a large bottle where they were 

 allowed to rest. Thej^ exhibited at first the characteristic sluggishness 

 which follows the absorption of chloroform, and it was manifested in 

 various incoherent movements. When they had entirely recovered from 

 the effects of their being subjected to the chloroform, their movements 

 were watched with interest. The fishes operated upon, it was observed, 

 swam with great slowness and hesitancy in the jar, evidently feel- 

 ing their way ; while those in which the lateral line was perfect passed 

 through the water and between obstacles with little or no diminution of 

 speed. It seemed evident to M. De S^de, as a result of his experiments, 

 that the lateral line has a tactual or sensitive function and supple- 

 ments or supplies the place of vision. The lateral line takes cogni- 

 zance of the currents and other movements of the water and the fish 

 knows its own swiftness and how to regulate it. Moving in an ele- 

 ment agitated without cessation, it perceives the least disi)lacement; 

 living in the midst of enemies which surround it on all sides it becomes 

 conscious of their approach by the slightest movements of the water. 

 The lateral line is, then, the result of an adaptation to aquatic life, an 

 adaptation which ceases with this mode of existence and disappears, 

 as we know is the case in the amphibians, when the animals become 

 adult and leave the water. The organs of general sensibility, these 

 tactual corj)uscles, are grouped in a more delicate apparatus, affecting 

 special dispositions absolutely different from those which characterize 

 the other organs of the definite senses. It may be said, therefore, that 

 in the lateral line a sixth sense in the full meaning of the word is de- 



