Ta>/l<ir: Nevromot or Apparatus in /,'//y)/o/<x 431 



EXPERIMENTAL 



'1'ln 1 following results are from experiments made on several 

 hundred Kui>ltcs patdln. Of those experiments. Ml") weiv recorded 

 with fairly extensive notes mi the exact location and nature of the cut 

 and on the animal's reactions before, during, and after the operation, 

 allowing several minutes for its recovery from the shock effects. The 

 various cuts include: (1) 1 ransoctions i dividing the animal in any 

 piano at right angles to its long axisK i iM excisions of external 

 organelles with or without a portion of the body, and i'8) incisions in 

 the liody or oral lip in any plane. Efforts were made also to ascertain 

 some of the physical properties of the pellicle and of the librillar 

 system. 



PELLICLE 



This membrane which completely envelops the body and oral lip of 

 Kiil>lnttx ixilillii is firm, fairly tough, and sufficiently rigid to main- 

 tain constantly the normal form of the body and lip. even when the 

 animal is subjected to a considerable stress from changes in water-glass 

 surface tension or to the applied pressure of a flexible needle. Figure 1 

 shows tlie extent of an incision fully two-thirds the width of the body, 

 yet this animal continually kept its normal shape during a half-hour 

 of devious movements through the water. In making dissections the 

 toughness of the pellicle requires the use of needles with rather stiff, 

 short points. Long-pointed, very flexible needles are ineffective. 



The extensile property of the pellicle is quite obvious in an animal 

 which has gorged itself with food until the body is conspicuously 

 bulged. If such an animal be subjected to a gradually increasing 

 pressure by the surface tension method previously described, just 

 sufficient to cause the egestion of a few food particles through the 

 pharynx, then as the needle is slowly removed the pellicle may here 

 and there become wavy or wrinkled. "Within a few minutes the 

 wrinkles usually entirely disappear. The elasticity of the membrane 

 may be readily demonstrated by applying a fairly flexible needle the 

 full width of the body when, with due pressure there occurs a con- 

 spicuous bending of the body over the needle. Upon releasing the 

 pressure the body at once resumes its normal shape. This may be 

 repeated successively many times. If. however, the animal has been 



