5 GEORGE V. SESSIONAL PAPER No. 39b A. 1915 



II. 



THE PLANKTON DIATOMS OF THE BAY OF FUNDY. 



By L. W. Bailey, LL.D., F.R.S.C., Etc. 



Emeritus Professor of Natural History and Geology, University of New Brunswick, 



Fredericton, N. B. 



(Plates I, II, and III.) 



The Plankton Diatoms constitute a group of peculiar interest in a division 

 of miscroscopic plants which, in all its branches, afford to the naturalist a field of 

 pleasurable and instructive study. 



The term ' 'Plankton" is one which is applied to the entire assemblage of 

 minute, mostly microscopic organisms, including both plants and animals, which 

 are found, often in vast numbers, swimming or floating freely, in the waters of 

 ponds, lakes or in the open ocean, having no connection with the solid earth, but 

 deriving their food supply from the .medium in which they live. So far as the 

 animal kingdom is concerned this floating population embraces members of several 

 groups, such as Infusoria, Foraminifera, and Radiolaria, together with larval forms 

 of Echinoderms, Annelids, Polyzoa, Crustacea and Mollusca, but, as regards plant 

 life, this is confined, with the exception of the small group known as the Peridineae, 

 to the family of the Diatomaceae. These are minute unicellular algse of which 

 the most notable peculiarity is the secreting of a siliceous shell or lorica, determining 

 their form and strength, and which is practically indestructible. 



Existing as they do in such enormous numbers in the purer oceanic waters, 

 the plankton Diatoms constitute a very large part of the food of higher oceanic 

 organisms, as is proved by the fact that they are found in such large numbers in 

 the stomachs of marine animals such as echinoderms, Crustacea, molluscs and 

 even fishes. Even where these animals are not themselves direct plankton feeders, 

 like the members of the herring and mackerel families, they nevertheless rely for 

 their nourishment upon smaller animals, Copepods and the like, which are thus 

 supported, so that the Diatoms may very properly be regarded as affording the 

 basic food supply for marine life, even in its highest forms. 



The features which especiafly characterize the so-called Plankton Diatoms 

 are those of their adaptation to a life of flotation. This is partly effected by arelative 

 reduction in the amount of silica contained in their cell walls, reducing their specific 

 gravity, but mainly in other ways, such as by the natyre of their forms or the 

 development of expedients which favor buoyancy. Thus in certain genera {Cos- 

 cinodiscus, Adinocyclus, Adinoptychus &c.) the form is that of a nearly flat or 

 slightly convex disc, exposing a large surface in proportion to the thickness of the 



