PLANKTOX DIATOMS IN ST. AXDREWS WATERS 49 



IV. 



Plankton Diatoms, their Distribution and Bathymetric 

 Range in St. Andrews Waters. 



BY 



Clara W. Fritz, B.A., M.Sc. 

 Principal East Angus Academy. 



(With three plates.) 



INTRODUCTION 



If a bottle of water be drawn from the sea and examined with the naked eye nothing 

 presents itself but the clear, sparkling liquid; but if this same sample be centrifuged for 

 half an hour and the residue examined under the microscope, it will be found that 

 many organisms of unparalleled beauty have been extracted. Chief among these are 

 the diatoms, unicellular plants, exquisite in beauty of symmetry and design. The 

 object of the investigations recorded in the following pages is to add some facts to 

 the present knowledge of these interesting forms. 



Collections of material were made throughout the year from October, 191G to 

 October, 1917, at various points in Passamaquoddy bay and the adjoining waters of the 

 the bay of Fundy. Careful examination of these has revfealed the presence of eighty- 

 two species, representative of twenty-six genera. Material collected during the 

 different months was found to vary greatly. Attention was, therefore, given to the 

 seasonal distribution and relative tibundance of the many forms. Ordinary tows were 

 taken at the surface and at a depth of from five to six metres, but, during the summer 

 of 1917, a series of samples was drawn from certain- stations at various definitely 

 recorded depths, and the contents examined in order to ascertain the bathymetric 

 range of species. 



Eighty-two species were found, and figures are furnished of those' which are rare, 

 or, owing to their similarity, difficult to classify. The system of classification used 

 is that introduced by W. L. Smith and followed by Van Heurck (1) and by the Chal- 

 lenger Report (3). 



I desire to take this opportunity of expressing my thanks to Dr. A. Willey, under 

 whose guidance the problem was commenced; to Dr. A. Gr. Huntsman, Director of the 

 Biological Station, and to his assistants, for their careful attention to the collection 

 of material; and to Prof. C. M. Derick for assistance and suggestions, which she has 

 kindly given. , 



Locality and Collection of Material. 



Passamaquoddy bay is situated at the south west corner of New Brunswick, 

 where it serves as ^ boundary between that province and the state of Maine. Into 

 it empty the waters of the St. Croix river; and its waters are in turn mingled with 

 those of the bay of Fundy by the ever-changing tides which sometimes reach a height 

 of twenty-four feet. A group of islands, of which the largest are Deer and Campo 

 Bello, form a partial barrier, through which the tid'es flow swiftly and with force. 



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