282 Mr. E. A. Mincliin on the 



point to tlie Cuvierian organs being simplj, as Herouard 

 sup])oses, a modified portion of the respiratory tree. 



Tlie iiabit possessed by so many Holothurians of ejecting 

 tlie intestines when stimulated is too well known to require 

 description. This evisceration seems to be almost a normal 

 liabit, since viscera of Holothurians are frequently fished up 

 by fishermen. At Plymouth I often offered ovaries and other 

 portions of the viscera of Holothurians to anemones and other 

 animals in my tank. I did not kecj) any careful record of 

 my experiments ; but I can only say that the viscera were 

 often immediately swallowed by anemones or seized hold of 

 by other animals, but always rejected again in a few minutes. 

 'J he im])rcssion 1 obtained was that these viscera were ex- 

 tremely unpalatable to the majority of animals. I think this 

 idea, if carried out by further experiments, would give us 

 some clue as to the use of this curious habit. If any rapa- 

 cious dogfish or other animal attacked a Holothurian and 

 caused it to eject its viscera, it would in all probability, after 

 tasting them, never repeat the experiment*. The Holo- 

 thurian, on the other hand, appears to suffer but little harm 

 from its evisceration, since it is certain that the whole of the 

 viscera can be regenerated under normal conditions. Never- 

 theless the habit of throwing out all the viscera must be an 

 exceedingly expensive one, and the view I take of the 

 Cuvierian organs is that they are sim))ly a 2>(^rlton of the 

 viscera special!?/ modijied for ejection. Their position, near 

 the base of the respiratory tree, is one where they would be 

 the first organs to be ejected, as Herouard has remarked. 

 Their anatomical relations show them, as stated above, to be 

 only specially modified portions of the respiratory tree. 

 Possibly they at first retained their respiratory function and 

 were only distinguished by the possession of an external layer 

 of mucous secreting gland-cells, which increased their unpala- 

 tability. At first merely passively offensive, they ultimately 

 by further modification became aggressively so, as in Holo- 

 thiiria nirjra. The steps from such an hypothetical initial 

 stage to the highly modified organs of the latter form it is not 

 in my power to trace. Before that could be done more infor- 

 mation is necessary as to their structure and the exact method 

 in which their elongation is brought about in this and other 

 forms. 



* Here one may draw attention to the intensely bright coloration of 

 the internal organs of Holothurians, which are certainly exceedingly con- 

 spicuous objects when ejected. May not this probably be a case to bo 

 brought under the heading of " warning coloration " ? ' 



