W. C. Mcintosh on the Azoic-Mud Theory. 11 



" Porcupine," Dr. Carpenter, who assumes the entire respon- 

 sibility of this part of the Report*, has advanced the theory 

 that it is the turhidity of the hottom-water which renders the 

 deeper parts of the basin of the Mediterranean barren of Hfe. 

 '^ All marine animals," he says, " are dependent for the aera- 

 tion of their fluids on the contact of water either with their ex- 

 ternal surface or with special (branchial) prolongations of it. 

 Now if this water be charged with suspended particles of ex- 

 treme fineness, the deposit of these particles upon the respiratory 

 surface will interfere with the aerating process, and will tend 

 to produce asphyxia." He further cites the case of oyster- 

 beds, which cannot be established in situations to which fine 

 mud is carried. He, moreover, points out the important bearing 

 this theory of his will have in regard to the vast azoic deposits 

 of the geologists, who, since the lapse of Pi-of. E. Forbes's 

 views as to the absence of animal life at great depths, have 

 been puzzled for a solution of the difficulty. Such a theory, 

 of course, ought only to be built on well-ascertained facts, 

 some of which, however, do not seem quite in agreement 

 therewith. 



Thus Terehellce and Gephyrea in vast numbers are charac- 

 teristic of muddy beaches, such as those between St. Peter 

 Port and St. Sampson's, in Guernsey, and near Rat Island, 

 Herm. Not only th-ese, but many other annelids are found no- 

 where else than amongst mud or muddy sand, and this is often 

 of such a nature that the sea-water which covers them must 

 always be loaded with minute particles of mud. So distinctly 

 is this the case, as at Lochmaddy, that the fronds of the sea- 

 weeds (both those covered and those' uncovered by the tide) 

 in quiet creeks are coated with a deposit of fine mud. Yet 

 marine life, from sponges upwards, is nowhere more abundant 

 than in such muddy regions. Indeed the contrast in this re- 

 spect between these creeks and the rocks washed by open (not 

 rough) water is marked. 



Certain mollusks, it may be true, like very young salmon, 

 do not thrive in muddy water, yet some of the most delicate 

 and beautiful annelids, with the finest branchial plumes, live 

 amongst the most tenacious chalk-mud, as it is called, which 

 it has been my lot to encounter. Yet these annelids are so 

 sensitive to other impurities that a very slight admixture of 

 fresh water (although the supply be taken from the sea) is 

 instantly fatal, as I, unfortunately, have reason to remember. 

 The habits of the littoral annelids are also instructive in this 

 i-espect. Many of the Folynoidoi^ O^hiodromus^ numerous 

 Nereid^je., lAimhrinereis^ the large Marphysa sanguinea^ Onv- 

 • Proc. Roy. Soc. No. 125 (1870), p. 202. 



