178 



Transactions of the 



[Sess. 



Organism experimented on. 

 Collozoum inerme . 



Velella 



Anthea cereus var. plumosa . 

 Do. var. amaragdina 



Ceriactis aurantiacus 



Do. 

 Aiptasia chamaeleon 

 Helianthus troglodytes . 

 Actinia cari .... 

 ,, mesembryanthemum . 

 Sagartia parasitica . 

 Cerianthus . , . . 



Red Gorgonia verrucosa . 

 White Gorgonia verrucosa 



Present 



Appreciable- 

 ieties. 



-physiological var- 



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



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

 animal tissues by exosniosis : 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 Algse remove COj 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 Algte 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. Lankester 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, Avhereas not more than 25 per cent is got from con- 

 sortial Algaj, 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 Algte is the 

 most common of Sea Anemones, while Eadiolaria with yellow cells 

 are more common than those without these structures. 



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

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

 the Forammifera, are thus chiefly maintained, 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 enormoiis numbers, afford in a large degree food-material 

 to the surface animals of these regions. 



