370 F. AV. GAMBLE AND FREDERICK KEEBLE. 



Bourne, Fowler in litt.^) ; and it has been snggosted (Brandt, 

 1882 ; Hickson, 1889) that these animals subsist, at least 

 during their adult stage, on the plastic products of their 

 yellow or green cells. Proof of such holophytic nutrition is, 

 however, still to seek. The experiments made by Brandt 

 (1882) on anemones and Radiolaria, and supposed by hira 

 to afford the desired proof, have been repeated by Famintzia 

 (1889, 1891), and have been shown to be susceptible of 

 a different explanation. Famintzin concludes that, if the green 

 and yellow cells of these animals subserve nutrition, this 

 nutrition is only effected by tlie digestion of the coloured 

 cells and their contents. Nevertheless the translocation 

 theory has been and is widely accepted. If, then, we can 

 show that the highest ex])ression of " symbiosis," that seen 

 in Convoluta, is not accompanied by abstention from active 

 feeding on solid bodies, we shall have succeeded not only 

 in refuting a general error, but in reopening the question of 

 nutrition in other cases of anima and algal associations. 



2. Observations of the Authors. 



Convoluta feeds and feeds voraciously. From the time 

 of hatching to the period of maturity it enjoys a remarkable 

 catholicity of taste. Diatoms, unicellular algae, spores of all 

 kinds, grains of sand, and colonies of bacteria are ingested 

 with equal avidity. Nor does it refuse artificial ''food." 

 Litmus, methylene-blue, congo-red, starch, lamp-black, ai\d 

 indigo are absorbed and distributed as though they were 

 nutritious substances. The accompanying figures (PI. 30, 

 figs. 4 — C) demonstrate the presence and " digestion " of 

 various of these substances. 



When the period of maturity arrives, Convoluta adopts a 

 new mode of nutrition. Almost every adolescent and adult 

 specimen of a colony, if examined at low tide, contains one or 

 more rounded brown masses in the central tissue of the 



1 Diicrden, 'Memoirs Nat,. Acad. Sci.,' AVasliington, vol. viii, 1902, 

 " West Indian IMadrepoiian Corals," lias suggested that corals feed at night, 

 but lias found no food. 



