244 W. J. Ceozibb, 



usual), or (if the animals were in very poor tone) through holes in 

 the body- wall made by a process of local degeneration very similar 

 to that which occurred when death was brought about by heating^ 

 and not marked by any great muscular activity. The time required 

 for the completion of the act of autotomy varied greatly with the 

 experimental conditions, occupying from a few minutes to an hour 

 or more. 



1 have been unable to discover the exact circumstances which 

 determine the casting out of the internal apparatus; once started^ 

 however, the principal factor involved in forcing out the vicera is 

 a slow muscular peristalsis working on the pressure of the fluid 

 in the body-cavity. When an animal was picked up and handled, 

 strong muscular contraction forced water out through the cloaca, 

 and as the aperture was quickly closed considerable internal pressure 

 was developed. If now a cut was made in the body-wall, or if the 

 animal was divided transversely by a sharp clip with scissors, part 

 of the viscera might be suddenly extruded; but this is not to be 

 regarded as an act of autotomy; evisceration sometimes followed, 

 hours after the operation, though mutilation did not invariably lead 

 to this result (cf. Torelle, 1909). 



Exp. 72,1. 



July 14. Twenty-three specimens had part of body removed — anterior 

 end, 13 cases; posterior end, 10 cases. Of these, 7 autotoraised part or 

 all of the gut after periods ranging from 10 min. to 14,5 hrs. The 

 remainder regenerated without autotomy. All the animals were kept under 

 practically identical conditions, in aquaria with normal animals which did 

 not autotomise. 



The only stimulus, or complex of stimuli, that invariably pro- 

 duced autotomy was the stagnation of the seawater in which the 

 animals were living; but individuals kept in aquaria under con- 

 stantly running water occasionally eviscerated also, after they had 

 been in the laboratory for some time. With the idea that depletion 

 of the available oxygen or the accumulation of some excretory pro- 

 duct was responsible for autotomy in ''stale" seawater, experiments 

 were made with boiled seawater ^), and with w^ater to which carbon 



1) These experiments were carried out using seawater which had been 

 boiled, the loss by evaporation made up with boiled rain water (volumes 

 corrected for temperature expansion) , and allowed to cool in full sealed 



