_Figs._ 1. and 2. Transverse section of the human clavicle (collar bone), showing Haversian canals, concentric laminæ, and concentric arrangement of bone cells--3. Transverse section of the femur of an ostrich--4. Transverse section of humerus (fore-arm) bone of a turtle, Chelonia mydas--5. Horizontal section of the lower jaw-bone of a conger eel, in which no Haversian canals are present--6. A portion of the cranium of a siren, Siren lacertina--7. Portion of bone taken from the shaft of humerus of a Pterodactyle, showing elongated bone-cells characteristic of the order Reptilia--8. Horizontal section of a scale, or flattened spine, from the skin of a Trygon (sting-ray), showing large Haversian canals, numerous wavy parallel tubes, also bone-cells with canaliculi communicating as in dentine.
Prefaces, page vi., line 22 _Insert_ “a” _into_ “admitted.” " " x., line 13 _Insert_ “the” _before_ “assistance.” " " xii. _Insert_ “for” at commencement of line 24. Page 33, line 13 _For_ “Rabbit” _read_ “Kitten.” " 486, 4th line from bottom _Strike out_ “The late.” " 511, two lines from bottom _For_ “Plate XIII.” _read_ “Plate XVI.” " 584, 5th line from bottom _Insert_ “Stalk-Eyed” _before_ “crustaceans.” " 624, line 12 _For_ “or” _read_ “and.” " 633, Plate VII. Numbering of figures-- _For_ “152” _read_ “158.” _For_ “152a” _read_ “152.”
(Professor Abbe, erroneously referred to more than once as “the late” is, the author is happy to say, in excellent health).
The instrument known as the Microscope derives its designation from two Greek words, μικρὸς (_mikros_), _small_, and σκοπέω (_skopeo_), _to see or observe_; and is an optical instrument by means of which objects are so magnified that details invisible or indistinct to the naked eye are clearly seen. Its origin, so far as yet can be traced back, seems to be of a doubtful nature. It is tolerably certain the ancients had little or no conception of the magnifying power of lenses; this may be surmised from their writings. The elder Pliny incidentally states that the physicians of his day cauterised by means of “a globe of crystal.” The learned Greek physician, Galen, however, demonstrates conclusively that in the first and second centuries of our era the use of magnifying lenses was quite unknown either to Greek or Roman. Moreover, the writings of Archimedes, Ptolemy, and other learned men, show that, although they had some idea of the action of refraction at plane surfaces, as of water, yet of the refraction at curved surfaces they had formed no conception. Indeed, they refer quite indiscriminately to the spherical form, or the disc, or the plane surface of the water, but not one of them speaks of the lenticular form, or the curvature of their surfaces.