87 



to its they are the fighting members of this ..republic of reflexes". 

 Yet they will never attack any part — tissue, pedicellariae or 

 spines — of the animal which bears them nor of animals of the 

 same species. This phenomenon has been called by von Uexkiill 

 ..autodermophily" and he explains it as the result ot a negative 

 chemotropism towards some substance, which he calls ..auto- 

 dermine". Uric acid, the toxic substance present here, might be 

 the autodermine. in fact the substance can be dissolved away 

 by means of hot water, after which a spine of the animal 

 itself is attacked just as vigorously as anything else. It may 

 be however that in this case we "have to do with some other 

 substance as yet unknown ; the gemmiform pedicellariae also 

 contain toxic substances in their ..poison-glands" (von Uexkiill 

 129)), the bite of one of them may stop the frog's heart, kill 

 the ischiadicus etc. Little animals (marine snails etc.) are killed 

 at once. C u e n o t has come to the conclusion that the toxix 

 substance was secreted by certain glands of the skin, called 

 ..glandes muriformes". Parker 96) could kill young animals, 

 e.g. cats, by means of extracts of the skin of starfishes '). 



Other experiments of Dr. Hiroshi Ohshima. unpublished 

 as yet, in which touching the skin of Arbacia made their eggs 

 unfit for fertilisation and, indeed, proved to be lethal for them, 

 may furnish additional evidence in favor of my view. If one 

 removes the skin of Arbacia from the shell and tests a watery 

 extract of it for uric acid, one invariably gets a positive result. 



Further experiments will be necessary for a definite decision. 



Note: 1. There is one other phenomenon which I want to 

 mention in connection with this chapter. I have observed it 

 frequently but have not found it mentioned anywhere in the 

 literature. 



If one takes a starfish from an aquarium and cleans it tho- 

 roughly with a clean towel, it is as dry as dry can be. Keeping 

 it for some time in his hand, one can observe that water 

 begins to exsude through the skin. After a little while one 

 observes, especially on the aboral side of the arms, long lines of 

 water-drops. This process goes on until finally drop after drop 

 falls from the tips of the arms. Meanwhile the arms loose 

 their rigidity. 



Whether or not this process is a normal one, I do not dare 

 to decide. It might be due to the breakiag of the papulae or 

 other thin membranes under the internal pressure of the peri- 

 visceral fluid. It may. however, also be a process which takes 

 place under normal conditions and then it must be a great 

 help in excretion, unless the papulae etc. are completely semi- 



1) Notwithstanding its toxicity the skin of the starfishes carries parasitical 

 Protozoa and a Caprella species, which must in that way have a kind of natural 

 immunity for their poison. 



