OP SENSATION AND THE SENSES. 479 



With grasshoppers I have made the following experiments. 



A small Gryllus (Acrydium, Lat.) I opened in the breast, between 

 the intermediate and posterior thighs, and removed the large ganglion 

 lying there. The insect thereby immediately lost the mobility of the 

 posterior extremities, and was also very much enfeebled, but yet 

 crept about by means of its four anterior legs. Having accidentally 

 soiled its antennae, it made stroking motions towards them with its 

 left anterior leg to cleanse them, and upon my taking it up by them, 

 it made very active exertions with the anterior legs to free itself. 

 I now made an incision in the same individual through the mem- 

 brane of the neck, whereby the nervous cord was separated, but 

 the oesophagus not injured. The creature at first still moved its 

 anterior legs, and in them there was a powerful reaction upon pressure, 

 and it trembled for a time afterwards, but otherwise exhibited few 

 signs of life ; it lay lifeless upon one side ; it did not even lie upon 

 its belly ; but yet there were still catchings in the feet when nipped 

 with the tweezers, but not in the large posterior thighs. In ten minutes 

 the motion of the legs considerably decreased, and in half an hour the 

 animal was entirely dead. 



A second somewhat larger and also very active Gryllus I again cut 

 through the membrane of the neck ; the insect, immediately after the 

 incision, made violent movements with its thighs, which cast off one of 

 its posterior legs; the other legs exhibited irritability as often as I 

 pinched them, but, after the lapse of a minute, it lost all voluntary 

 motion, it could no longer walk, and remained quietly lying upon its 

 side when so placed. In half an hour it was dead. 



I have besides made experiments in Diptera, namely, in some species 

 of Eristatis. 



I separated the nervous cord of a lively Eristalis ncmorum, closely in 

 front of the middle legs ; those legs immediately lost their motion as 

 well as the right posterior leg, but it still crept about by means of its 

 anterior legs and left posterior one. These motions continued, but its 

 course was not straight, but inclining obliquely to the left. I now 

 made the incision deeper, to be perfectly convinced that I had thoroughly 

 separated the nervous cord. The left posterior leg now lost its motion, 

 but the fly still crept with its anterior pair., but it could no longer fly, 

 as was the case upon the first incision. I now cut off its head ; imme- 

 diately all the motion of its anterior legs ceased, but the proboscis of 

 the separated head still throbbed when I drew it from the cavity of the 



