T H E A NNALS 



AN') 



MAGAZINE OF NATURAL HISTORY. 



[SECOND SERIES.] 

 No. 82. OCTOBER 1854. 



XXIII. — On the Mechanism of Aquatic Respiration and on the 

 Structure of the Organs of Breathing in Invertebrate Animals. 

 By Thomas Williams, M.D. Lond., Licentiate of the Royal 

 College of Physicians, formerly Demonstrator on Structural 

 Anatomy at Guy's Hospital, and now of Swansea. 



[With three Plates.] 



[Continued from p. 5/.] 



Structure of the Bronchia in the Lamellibranchiate Mollusks. 



The mist upon this branch of natural history which has survived 

 the brightening science of a bright century may indeed refuse 

 to be dissipated even by the achromatic microscope — the potent 

 wand of the modern observer. That which the calm eye dis- 

 cerns with clearness, and the understanding interprets with 

 confidence, though amplified many hundred diameters, is as 

 likely to be an immutable objective truth as any " instance " 

 within the sphere of the unassisted vision. Faith in the 

 verity of microscopic facts is a fundamental article in the 

 scientific creed of every living philosopher. The sphere of the 

 naked vision is exhausted : auother is opened by the micro- 

 scope. Minute descriptions of subtle and complex structures, 

 rendered possible only through its instrumentality, will prove of 

 as great service in the hands of the future lawgivers of science, 

 as the grosser narratives of the fathers of anatomy have already 

 proved in the founding of the temple in which the high priests 

 of natural theology now chant her service. 



The branchial structures of the Mollusca have never yet been 

 unravelled. The problem, though not impracticable, still awaits 

 solution. The system of the gills is a conspicuous element in 

 the molluscan organism. In apparent size they arc considerable. 



Ann. $ Mag. N. Hist. Ser. 2. Vol. xiv. 1G 



