1883-84.] EdinhurgJi Naturalists Field Club. 179 



Dr Karl Brandt, in 1883 (' Mt. Zool. Stat. Neapel.'), enunciated 

 the same physiological inferences as Mr Geddes reached, stating — 

 (1) that the assimilation products of living yellow cells partly serve 

 the animals ; and (2) that possibly assimilation is more rapid when 

 the Alga is inside the animal, because an abundance of CO2 is got 

 from the animal — the former of these propositions being based on 

 the action of iodine on CoUozoum, small starch granules having been 

 observed in the protoplasm of that organism. These granules were 

 chiefly found on the outer surface of, or in close proximity to, intact 

 yellow cells, and they agreed with the starch granules found in the 

 yellow cells. As to the action of the oxygen that is evolved by the 

 symbiotic Algte, as affecting the movements of the associated animals, 

 diverse views have been adopted by Mr Geddes and Dr Brandt. The 

 former believes that in sunlight this oxygen causes the animals to 

 move their tentacles as if they were subjected to mild stimulation — 

 too protracted hyper-oxygenation of Radiolarians, however, resulting 

 in sickness or death. Brandt (' Mt. Zool. Stat. Neapel.,' 1883) 

 maintains — 



(a) That Algae-bearing Actinise, when brought from diffuse to direct 

 sunlight, suffer no irritation if the temperature is not allowed to rise. 



(b) That Actiniaj heated from 26° to 36° C. move more actively, 

 whether the heat be derived directly from sunlight or whether it be 

 artificial heat; and that the same result follows whether A] gse are 

 present or absent. 



(«) That Algffi-bearing Anthozoa are killed in direct sunlight, not 

 by the oxygen produced, but by heat. 



(r?) That all Algte-bearing Actiniaj throw off a number of cells 

 when heated to 30° or 35° C, and that the yellow cells so extrava- 

 sated are capable of development or assimilation. 



Of the three classes of green animals, then, — namely (1), those con- 

 taining green pigment which is not chlorophyll, e.g., BoneUia; (2) those 

 containing chlorophyll in symbiotic Alga3, e.g., Anthea, Eadiolaria, 

 &c. ; and (3) those provided with intrinsic chlorophyll, such as 

 Hydra and Spongilla, — the latter class still remains shortly to be 

 considered. Various observers have considered the green corj^uscles 

 of Hydra and SpongiUa, and the results at which they have arrived 

 may be stated thus : — 



(1) Professor Semper of "Wurzburg ('Animal Life' — "Interna- 

 tional Scientific Series," p. 73) regards the occurrence of these green 

 bodies in animal tissues as a case " either of parasitism or of a com- 

 munity of two organisms so different as an animal with true tissues 

 and organs and a one-celled plant." 



(2) Dr K. Brandt holds the same views as Semper, and bases his 

 belief in their algoid nature on the following considerations : — 



(a) The green bodies consist of hyaline protoplasm, are provided 

 with a nucleus and curved chlorophyll granule, and are capable of 

 division. The green bodies were isolated by pressure, and their 



