64 



THE OOLOGIST. 



Note shape; optic nerve entering at 

 back part. The eye must he dissected 

 and examined under clear water. 



With small scissors, divide the eye in- 

 to an outer and inner hemisphere, 

 by carefully cutting through the coats; 

 separate the coats, leaving the humors, 

 &c, in the outer hemisphere; notice 

 the interior of the cup-siiaped part of 

 the inner hemisphere, the place of en- 

 trance of the optic nerve and the blood 

 vessels. Now make out the three lay- 

 ers of membrane of eye; the sclerotic 

 outside, the choroid and the retina, the 

 delicate membrane on inside of back 

 part of eye; how far does the sclerotic 

 coat extend? Its character in different 

 parts; how far does the retina extend? 

 The jelly-like substances in the eye are 

 known as humors. The one exposed is 

 the vitreous humor; looking from be- 

 hind into the outer hemisphere, note the 

 celiary processes, the dark "plaited" 

 part of the choroid coat; remove this 

 and notice the crystalline lens; turn the 

 hemisphere over and look from in front; 

 notice the transparent continuation of 

 tho sclerotic coat, the cornea; back of 

 this the iris, the membrane giving color 

 to the eye ; in centre of this, the circu- 

 lar aperture, the pupil; the fluid just back 

 of the cornea is the aqueous humor 

 remove the crystalline lens; note shape; 

 what is the effect when placed over a 

 small object? Put the lens in alcohol 

 for a few days, then see whether its 

 humor is arranged in layers like an on- 

 ion; compare the size of optic nerve 

 with some others of body, 



The opening of ear; the external audi- 

 tory meatus; the tympanic membrane 

 stretched across its inner part; remove 

 this; probe for the opening of the en- 

 stacian tube in mouth; the bony frame- 

 work of ear will be studied in the pre- 

 pared skull. 



The male urinogenital oi'gans. (see 

 Cut). The testis two white oval bodies of 

 variable size in the upper, posterior 

 part of body; the vos deferens, a tube 



leading frem them downward to the 

 cloaca; the kidneys, large dark red or- 

 gans above the testes; notice irregular 

 shape, lobed. fitting into cavitities in 

 bone; the ureter, going from each kid- 

 ney to the cloaca, the large blood tubes 

 connected with kidneys. The female 

 urinogenital organs. The ovary, a 

 number of capsules, each containing an 

 egg; these very in size; the oviduct go- 

 ing from ovary to cloaca; can you find 

 a rudimentary right oviduct ? 



The reproductive organs are most 

 conspicuous in old birds near breeding 

 time. The brain is best studied after 

 hardening in strong alcohol. After re- 

 moving skin and flesh from skull as 

 cleanly as possible; beginning at the 

 posterior part, with bone forceps or 

 knife, remove theskull frombrainbylittle 

 particles; (great care must be taken in 

 doing this, as a neat dissection of the 

 braiu is most desirable.) The large 

 cerebral lobes separated by deep fissure; 

 back of these the cerebellum; notice its 

 ridges, — gyri; on each side of cerebel- 

 lum, thejlocculus ; the pineal body on 

 the dorsal side of brain, in the triangu- 

 lar opening between cerebral lobe and 

 cerebellum; (read up on "pineal body" 

 from some good author,) the lobes on 

 each side, between cerebrum and cere- 

 bellum are the optic lobes;, note the un- 

 der side, the peculiar way in which the 

 optic nerves leaves the lobes; the ol- 

 factory lobes connected with the under, 

 anterior part of cerebrum. Compare 

 this with other brains, as a rabbit or cat, 

 fish, frog, snake, or that of man. 

 Now notice the cranial nerves leaving 

 the brains. Some parts ol the brain 

 contain eavities. 



These are known as "-ventricles." 

 How many are in the cerebral lobes ? 

 Are there any in the optic lobes ? Find 

 these. Several other points will be 

 noticed when making dissections as 

 shown in the plate accompaning this 

 article. Jno. Snyder, 



Waterloo, Ind. 



