214 LECTURES ON 



inhalent and excurrent. Could we see in those dark regions of the 

 abyss, and could we make the flow of water evident by colored par- 

 ticles, we should Avonder to see such a commotion going on a round 

 our oyster valve; so many eddies, Avhirlpools, "lost channels/' con- 

 flicting currents, produced by hidden but evidently powerful causes — 

 the muscular energy of the soft creatures inside the rocky holes. It 

 is said by sanitary reformers that the great questions of public health 

 resolve themselves into two problems— how to bring pure water in, 

 and how to carry foul water out. These problems our Gastrochsena 

 has most satisfactorily solved. The pipe muscles are the engine, 

 pumping the water at high pressure; the siphon is the main Avhich 

 keeps the reservoir within on full supply; from this the service pipes 

 of blood vessels branch to every atom of the body. Dissolved in 

 the Avater is the ever- vivifying oxygen, and SAvimming in every drop 

 are the dainty infusoria. The water, cleared of its nourishment by 

 the net-like lips, and of its renewing functions by the reticulated 

 filriis which float like fairy tissues in the liA'ing stream, (the plate gills 

 of our bivalve,) hoav receives its dose of heavy carbonic acid, as Avell 

 as the Avasted tissues of the body. Meanwhile it has been Avashing 

 round the house, and has received its particles of almost invisible 

 dust which the young scraper has cleared out. The sand of the street, 

 as well as the drainage of the house, having been thus poured into 

 the sewer, it is at once flushed out by the same high pressure of the 

 incurrent water, and is expelled by the muscular force of the second 

 siphon. Thus the house is always washed, the drains always cleansed, 

 the air always fresh, the table ever spread with dainties, and our 

 tunneler finds his refuse always carried away without the expense of 

 tram-road or even the labor of wheelbarrow. Truly, nature's works 

 are as perfect in their minutise as in the guiding of the stars. 



As the animal increases in size his instincts (unlike those of many 

 other borers) lead him to Avork deeper, and retire farther from the 

 outer world. He adopts the sentiment of La Fontaine's hermit rat, 

 "Les choses d'ici bas ne me regardent plus." As he advances, he 

 carefully fills up the empty space behind with layer after layer of 

 shelly matter, lest the spaAA r n of obnoxious individuals should enter 

 and occupy the deserted mansion. Occasionally some unlooked for 

 event disturbs the even tenor of his existence. His diffused sensa- 

 tions, not specialized into the functions of sight and hearing, become 

 conscious of the slow but steady approach of some intruder on his 

 peace; it may be his brother, working from the opposite side of the 

 oyster; it may be a creature of some other race. It is all one to 

 him; he displays neither blind partialities, nor special aversions; all 

 he asks is to be let alone; and he gives his own answer by making a 

 sudden turn. His neighbor does the same, and the great event of 

 their two lives is over. They never fight. 



The same siphonal currents carry forth in their season the fecund- 

 ating influences which reneAv the species. They enter the branchial 

 cavity of the other sex: whence, also, the matured eggs are carried 

 forth. 



