101 



siderations. There is still another thing to be thought of, sugges- 

 ted by a paper of Bohn 10). This eminent French biologist 

 shows that starfishes can produce Oj in the daylight. The 

 enormous quantity of pigments, present in Echinoderms (von 

 Fiirth 138), p. 518) might have one among them with respi- 

 ratory importance. The same thing had previously (CR. Acad. 

 Sc. Paris. 19 Oct. 1908) been demonstrated by the same author 

 for certain actinians (A. equina, Sagartia erythrochila), even when 

 they do not have any symbiotic algae. It seems, according to him, 

 to be a general property of lower animals. In oxygen-poor water 

 the starfishes suffer in the dark, even as far as to autotomise 

 their arms. In the same water in diffuse daylight there is pro- 

 duced in five hours as much as 1 .4 mgr. of O2 in excess of the 

 quantity consumed by respiration; the animals are perfectly 

 normal. In supersaturated sea water much mure O2 is consumed 

 in the dark than in the light. Several controls have been made 

 so as to exclude the action of chlorophyll-carrying micro- 

 organisms, of an incidental introduction of Oj and of a sick 

 condition of the animals used, but the same result invariably 

 is obtained. Starfishes need much oxygen and suffer in water 

 which does not contain more than 3 mgr. of oxygen, but they 

 endure large quantities of potassium cyanide, a property which 

 Bohn, Drzewina and others always found in animals with 

 anoxybiotic respiration. 



Unexpected as this result may seem, it is made highly probable 

 by the few, but critical and sufficiently controled experiments 

 given. In the beginning of this chapter I mentioned that 

 P litter finds in his Holothurians a big difference in CO2 pro- 

 duction in the light and the dark. This phenomenon has its 

 minimum in the freshly caught animals, as we can see from 

 the table 14. The figures in this table indicate the oxygen 

 consumption. 



Table 14. From- Piitter. 



In dark. 



In hght. 



Ratio. 



P' month. 

 2<* month. 

 3"* month. 



31 

 61 

 60 



31 

 38 

 23 



1 :1 

 1 : 1.6 

 1 :2.6 



It is, as Piitter says, hard to imagine that the metabolic 

 processes can be influenced to such an extent by light ; ana- 

 logies from other parts of the animal kingdom fail, unless we 

 assume, that also by these Holothurians Oo is set free in the 

 light in some way. 



The possibility of the presence of symbiotic algae does not 

 seem to be very great. The only thing that is left, is the active 



