178 



Transactions of the 



[Sess. 



Organism experimented on. 

 CoUozoum inerme . 

 Velella .... 

 Anthea cereus var. plumosa 



Do. var. smaragdina 



Ceriactis aurantiacus 



Do. 

 Aiptasia chamEeleon 

 Helianthus troglodytes . 

 Actinia cari . 



, , mesembryanthemum 

 Sagartia parasitica . 

 Cerianthus 



Red Gorgonia verrucosa . 

 White Gorgonia verrucosa 



ieties. 



Mr Geddes's inferences from his experiments are these : — 



(1) The starch of the Algas, when dissolved, passes out into the 

 animal tissues by exosmosis : the animal at the same time possesses 

 much amylolitic ferment capable of converting starch into sugar. 



(2) When the Algse die they are digested by the animal, and so act 

 as a food supply. 



(3) When alive the Algfe remove COo and nitrogenous waste, thus 

 performing an intracellular renal function — the abundance of these 

 substances probably accelerating, at the same time, their powers of 

 multiplication. 



(4) The AlgJB evolve oxygen, which in time accelerates the vital pro- 

 cesses of the animal, and so functions as stationary haemoglobin in the 

 blood — a substance that has also been found by Prof. Laukester sta- 

 tionary in the tongue muscles of MoUusca, &c. — (' Brit. Assoc.,' 1871, 

 p. 140.) 



(5) Since free Diatoms and Seaweeds evolve from 40 to 70 per 

 cent of oxygen, whereas not more than 25 per cent is got from con- 

 sortial Algee, it follows that the animals use up part of the oxygen as 

 it is being formed. 



(6) There is reason to believe that consortism is favourable in the 

 struggle for existence — inasmuch as Anthea cereus with Algae is the 

 most common of Sea Anemones, Avhile Eadiolaria with yellow cells 

 are more common than those without these structures. 



(7) Consortism is important in the economy of nature, "for, 

 since the Eadiolarians, and doubtless also, at least to a large extent, 

 the Foraminifera, are thus chiefly maintauied, and since they serve 

 as nutriment, directly or indirectly, to most of the higher pelagic 

 animals, the apparently disproportionate abundance of animal life 

 in the open sea becomes no longer enigmatical." It is also to be 

 borne in mind, however, as has been pointed out by Hooker, that in 

 arctic and antarctic regions in particular, the Diatomaceae, which 

 abound in enormous numbers, afford in a large degree food-material 

 to the surface animals of these regions. 



