60 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



shall be obliged to consider the conditions of life under which this microscopic oyster 

 food is produced. 



Similar relations are sustained by many other large aquatic to other microscopic 

 organisms. For example, it has been shown by the writer that the food of the sturgeon, 

 during its' larval life, is microscopic. In fact, were it not for this capacity of the larval 

 sturgeon to obtain other living organisms of small size, it could not reach those stages 

 of growth at which it is possible for it to feed upon larger organisms, and thus be 

 enabled to reach the adult condition. In short, were it not possible for the very small 

 larval sturgeon to find living forms small enough for it to capture and swallow entire, 

 it would not be possible for it to grow to those stages which lead to the adult state. 

 We thus realize that were there no microscopic organisms there could be neither 

 caviare nor smoked sturgeon. 



The same is true of the larval oyster. It is exceedingly probable that were there 

 no bacteria and monads still more minute than the diatoms upon which the adults 

 feed, the very young larval oyster could not find living food small enough to pass 

 into its exceedingly small mouth. The lowest and minutest organisms known, 

 therefore, probably enable the very young oyster to pass into the next larger stages of 

 growth, and thus absolutely secures this important mollusk against extinction. The 

 bacteria and monads seem, in fact, to be a kind of baby food for young oysters that 

 enables them to pass the critical stage of their very young infancy with safety. Bac- 

 teria should therefore not always be condemned. In the form of the yeast plant, and 

 as the bacterium of the butyric ferment, microscopic organisms may be vitally con- 

 cc ned in the production of bread and butter, no less than in the production of oysters. 

 While some bacteria, such as the cholera Spirillum, may be an agency concerned in 

 decimating the human family, other harmless species maybe the means of indefinitely 

 continuing the supply of the necessaries as well as the luxuries of the tables of man- 

 kind. It may not be amiss to remind an all too thoughtless public that, whether one 

 enjoys an after- theater supper in a splendid restaurant or a modest oyster "stew" at a 

 cheap lunch counter, the despised bacteria may be indirectly the means of ministering 

 to the mere enjoyments of the palate as well as the necessities of existence. 



The same is true of still more costly luxuries. Were there no microscopic 

 organisms upon which the larvse of the pearl-oyster could feed to carry them over the 

 critical stages of their infancy, there would be no pearls to ornament the show loving 

 human animal, since there would then be no true pearl-forming animal to produce 

 those gems. 



Coming to more prosaic and useful things, the fish-oil used in dressing leather, in 

 like manner, is largely the accumulation of the oleaginous matters once forming part 

 of the bodies of microscopic organisms, upon which oil-producing fishes and. cetacea 

 feed. Dr. Peck has lately shown that the much-abused menhaden, from which oil 

 and guano are produced, is a living filter that literally strains all its microscopic dia- 

 tomaceous and protozoan food out of the waters of the ocean wastes that it inhabits. 

 The oil-producing basking-skarks do the same. Whales that may produce upward 

 of two hundred barrels of oil live exclusively upon small pelagic organisms that must 

 themselves live upon still smaller ones. A single whale was found by Mr. Edwards 

 to have made its last meal upon shrimps, of which several barrels were taken from its 

 stomach. These shrimps had fed upon still smaller creatures that had been feeding 

 upon the microscopic life of the sea. Infinitesimal volumes of food are thus gathered 

 together in ocean wastes and assimilated in succession through a series of organisms 



