THE NATURAL HISTORY OF THE SEA. 395 



fact without details in an account of other matters in a 

 previous Fishery Board Report. Search was made by Mr. 

 Murray for evidence of these animals eating PeridiniecE, but 

 without success, possibly owing to the more easily destruc- 

 tible character of these organisms within the digestive tract, 

 probably to their escape in many cases from being devoured 

 by reason of their frequently spiny character. This seems 

 to be the more likely since he failed to discover traces of 

 spiny diatoms being eaten, and the beautiful sculpturing of 

 diatom shells may come to be reckoned with the thorns and 

 prickles of land plants as defences against animals ! That 

 young fishes themselves eat diatoms appears to be the case. 

 He took young sand eels, young flat fishes and young 

 clupeoid fishes, and reduced them to a fine ash which was 

 found to contain considerable quantities of different diatoms, 

 not broken as they would have been had they been eaten 

 previously by small Crustacea. Whitebait would appear 

 from these experiments to be worthily fed on the beautiful 

 diatom Coscinodiscus. As " all flesh is grass " in the strictly 

 physiological sense, so all fish appears to be diatom. 

 These organisms hitherto known to us as yielding the 

 material for dynamite, polishing powders, and the amuse- 

 ment of harmless old gentlemen with microscopes, must in 

 future be treated with becoming respect. 



It undoubtedly represents an advance in methods of 

 work when a fast mail steamer can be converted into a 

 plankton expedition by simply taking a passage on board of 

 her and pumping sea water from the deck hose through a 

 fine silk bag and retaining the filtered substance for exami- 

 nation. Messrs. Murray and Blackman (9) have done it even 

 more economically by capturing Captain Milner of R.M.S. 

 Para, providing him with the apparatus and a little instruc- 

 tion, and sending him forth to look in the Atlantic for objects 

 requiring an immersion lens to disclose their appearance. 



By this means they obtained for study not only the 

 Coccospheres and both kinds of Rhabdospheres, but Pyro- 

 .cystis as well — a remarkable haul of debateable organisms. 

 Their examination of them, briefly recounted, tends to con- 

 firm the view taken of them in the ''Challenger' Nai^rative. 



27 



