CHAPTER XI 

 Ocean Seasons 



One of the most obvious phenomena on land in our climes 

 is the rotation of the seasons. If we were suddenly let 

 loose from a prison in which for many years we had lost 

 count of time, and if our course were then directed to a 

 country garden, a wooded valley or a mountain marsh, 

 we could read at a glance by the presence of flowers, birds 

 or insects the season of the year. We can follow this 

 endless daily change in our gardens, in the woods, and in 

 ponds, but to many the seasons of the sea are a closed book, 

 save for the changes to be seen in that narrow fringe around 

 our shores, the tidal zone. 



It is for this reason that the subject is given a chapter 

 to itself, to emphasize the fact that there are seasons in 

 the ocean, and that in the causes of the seasonal changes 

 lie some of the most fascinating problems of marine research. 



Perhaps nowhere can the signs of the seasons be more 

 clearly read than in that drifting community of plant and 

 animal life known as the plankton. Anyone who takes 

 collections with the tow net at regular intervals of time 

 in the waters off our coasts will be struck at once by the 

 unexpected suddenness with which the composition of 

 the catches may change from week to week. He will see, 

 as it were, an ever changing panorama of life. 



In the early months of the year, March and April, when 

 the sun is climbing in the heavens and its light increasing 

 in strength, we note a very great change in the plankton 



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