1893.] NEW-YORK MICROSCOPICAL SOCIETY. 71 



men, is to a great extent only automatic or reflex action. What 

 we do we must do, owing to the contraction of our brain, and 

 so-called will plays a trifling part in controlling our actions, 

 mainly under the guidance of the frontal lobes of the brain. 



THE OCCURRENCE OF MARINE DIATOMS IN FRESH 



WATER. 



BY ARTHUR M. EDWARDS, M.D. 

 (Read February iiik, 1893.) 



Even the amoeba, that formless mass of jelly, begins somewhere 

 and somehow. The diatomacese have a beginning, but what that 

 beginning is, and when, and how, is uncertain. But when they 

 began, was it as inhabitants of fresh water, in ponds and rivers, 

 or of salt water, in the ocean ? This can be determined with a 

 certain degree of assurance by examining the strata where their 

 silicious loricas are preserved. 



Since I began studying the diatomacese, now some forty years 

 ago, their beginning was a subject of constant inquiry, and I 

 think I can now determine with positive certainty that their 

 origin was in fresh-water strata. 



The sea, that formed from the falling rain, was fresh, of course, 

 and became salt by the solution of hydrochloric acid and sul- 

 phurous acid, and Ihen, further, by the solution of certain salts 

 from the earth. After a time the rain which collected fell as 

 fresh water on the earth and formed ponds, lakes, and rivers. 

 But whether they or the salt sea were formed first is undecided. 

 Fresh-water diatomacese formed in some places first, and were 

 carried downward and became brackish and at last salt, as can 

 be proved by examining the strata, as I shall show. At least, such 

 is the inference. 



The gathering of which I speak now is from Hatfield Swamp, 

 on the Passaic River, New Jersey. It is about thirty miles above 

 Newark, following the tortuous course of the stream, but only 

 nine miles distant across the country, the Hatchung Mountains, 

 in two ranges, intervening. At Paterson are situated the Passaic 

 Falls, seventy feet in height, and at Little Falls, four and one-half 



