COMMENSALISM AND PARASITISM. 161 



of this Coral may in all cases be described as 

 crowded with " yellow cells." But as the 

 "yellow cells" are certainly of great physio- 

 logical importance to the Millepore, it is equally 

 certain that the secretions and the protection 

 afforded by the Millepore are of extreme import- 

 ance to the "yellow cells." In fact it is not 

 going too far to say that the Millepore and its 

 " yellow cells " are dependent upon one another 

 for their existence, and the naturalist might say 

 with a great deal of truth that this particular 

 Coral is not, strictly speaking, animal in nature, 

 but rather an animal and vegetable combination. 



Many years ago there was a bitter controversy 

 among learned men on the question of the animal 

 or vegetable nature of Corals. The great natur- 

 alist Linnaeus, who was appealed to for his sup- 

 port by both parties to the controversy, took up 

 a middle position, asserting that they were partly 

 of the nature of animals and partly of the nature 

 of plants, and hence the term " zoophytes," i.e. 

 animal-plants, came to be applied to them. There 

 can be no doubt that in the end the position in 

 the controversy, assumed by Linnaeus, became 

 untenable, and the supporters of the animal view 

 of zoophytes won all along the line. It is curious, 

 therefore, that we are now in a position, not to 

 support the view of Linnaeus, but to assert that 

 some Corals are essentially a combination of ani- 

 mals and plants. 



Plants are of use to marine animals, however, 

 in another manner. Mention has already been 

 made of the way in which many animals resem- 

 bling in colour, and even in form, certain kinds of 

 L 



