June 22, 1883.] 



SCIENCE. 



567 



of the ocean over which the Gulf Stream flows. 

 Instead of a deep channel, which has been pre- 

 viouslj' reported, our soundings show an exten- 

 sive and nearly level plateau extending from 

 a point to the eastward of Bahama Banks to 

 Cape Hatteras. Ofi' Cape Canaveral it is near- 

 \j 200 miles wide, and gradually decreases in 

 width to the northward until reaching Hatteras, 

 when the depth is more than 1,000 fathoms 

 within 30 miles of the shore. 



' ' This plateau has a general depth of 400 

 fathoms, suddenlj' dropping on its eastern 

 edge to 2,000 fathoms. The soundings in the 

 strength of the current were all taken with the 

 60-pound shot-sinkers, the time allowed for 

 the sinker to reach the bottom being less than 

 one minute to each 100 fathoms in depth. 

 Most of the soundings taken each side of the 

 stream when not in strong current were taken 

 with a 36-pound lead on the sounding-wire, 

 the lead being reeled back. ... It will be 

 observed from the bottom specimens that the 

 course of the Gulf Stream can almost be traced 

 hy the character of the bottom. 



" On each side of the stream the sounding- 

 cj-liuder brought up ooze. In the strength of 

 the current, the bottom was washed nearlj' bare, 

 the specimens being small broken pieces and 

 particles of disintegrated coral rock. This bare 

 portion was verj- hard, and the sharp edge of 

 the brass sounding-cylinder came up very much 

 dented and defaced." 



During the summer of 1882 the Blake, under 

 command of Lieut. -Commander W. H. Brown- 

 son, was engaged in sounding ofl' New-York 

 entrance. The charts have hitherto shown a 

 spot about 100 miles south-east of Sandy Hook 

 known as the ' 145-fathom hole.' In her sound- 

 ings, the Blake discovered this hole to have a 

 most remarkable character. 



Its depth varies from 150 to over 450 fathoms, 

 the bottom being mud ; and in about the centre 

 a knoll of mud, gravel, and shell i-ises up to 

 within 64 fathoms of the surface. The divid- 

 ing-ridge between the hole at its deepest point 

 and the deep water outside has a least depth 

 of 129 fathoms. There seems to be a continu- 

 ation of irregular character of bottom, which 

 extends from Sand}- Hook about south-east ; 

 for about 200 miles farther the depth is over 

 3,000 fathoms, surrounded hy very much shoal- 

 er depths. 



During the past winter the vessel has been 

 engaged in developing the limit and general 

 character of the great Atlantic basin between 

 Bermuda and Bahama, and along the outside 

 of the West India Islands as far to the east- 

 ward as St. Thomas. This cruise has been of 



great interest. The bed of the Atlantic is 

 shown to have a general depth of 2,700 or 2,800 

 fathoms ; and depths of over 2,000 fathoms 

 are found almost if not quite in sight of most 

 of the islands along the outside of the Baha- 

 mas, and even in the narrow passages between 

 them. In one place the 2,000-fathom curve 

 was found to approach the shore to within two 

 miles and a half, giving an inclination of the 

 bottom of over 38 degrees. 



Not the least gratifying point of interest of 

 this cruise was the successful sounding taken 

 at the enormous depth of 4,561 fathoms, which, 

 it is believed, is the greatest depth from which 

 bottom specimens and temperature have been 

 obtained. 



Tlie soundings shown on the sketch repre- 

 sent but a small part of the work performed 

 by the officers of the Blake, as only the char- 

 acteristic ones have been selected from a total 

 of nearly 2,000. During the time actuallj- en- 

 gaged in sounding, the Blake has steamed over 

 7,000 miles, and probably as much more in 

 going to the working-ground, and in gaining 

 positions after being obliged to abandon them 

 from heavj- weather, want of coal, or from 

 other causes. 



Bottom-soil specimens have been saved for 

 examination, and densities of the sea-water 

 obtained at nearly all the greater depths. 

 About 1,200 surface temperatures have been 

 taken ; and the observations of the tempera- 

 ture of the water between the surface and the 

 bottom will number about 1,300. 



THE PROTOZOAN PARASITES OF THE 

 OYSTER. 



M. Certes has recentlj- described the pro- 

 tozoan parasites or commensals of Ostrea 

 edulis and angulata, resorting to a method 

 used bj' the writer in studying the contents of 

 the stomach of the 0. virginica during the past 

 summer. A pipette is introduced through the 

 mouth of the animal into its stomach. After it 

 is filled with the brownish, dirty-looking con- 

 tents of the gastric cavity, the pipette is with- 

 drawn, and emptied upon a slide or compressor, 

 and the material carefullj' examined under the 

 microscope, in order to learn the nature of 

 the bill of fare of the animal, and to detect 

 the presence of endoparasitic organisms. As 

 found hy the writer in the American oj"ster, 

 M. Certes states that the oj'steris omnivorous. 

 Amongst the contents of the stomach, more 

 or less disorganized, grains of pollen, mites, 

 algae, crustaceans, diatoms, foraminifera, radio- 

 larians, and, at certain times of the year, a 



