GENERAL BIOLOGY 



II. MUSCLE. 



a. Tease out a bit of injected frog's muscle preserved in alcohol, 

 (i) It is composed of elongated fibres, some of which may be split 

 up somewhat into fibrilae. (2) Numerous blood capillaries are 

 found among the fibres. 



b. Examine with a high power : ( I ) Each fibre shows alternate 

 darker and lighter bands, (2) A delicate sarcolemma or structure- 

 less membrane envelopes each fibre and can be easily seen at places 

 where the fibres are broken or twisted. 



e. Tease out fresh muscle in salt solution and examine with 

 high power to note the above points ; treat with acetic acid and 

 observe the oval nuclei in the fibre. Draw. 



III. NERVE. 



a. Nerve fibres : Tease out a bit of fresh nerve in salt solution 

 and examine with a high power. Note: (i) Well defined fibres, 

 each with a double contour, together with white fibrous tissue 

 make up the mass of the nerve. (2) Each fibre has a highly re- 

 fractive border (medullary sheath) and a central homogeneous 

 axis cylinder, well seen in torn specimens where also the very 

 delicate, innermost membrane (primitive sheath), may be some- 

 times made out. 



b. Ganglion cells: Examine prepared specimens of ganglion 

 cells that have been stained to make out the structure of the cells. 



Draw a nerve fibre and a ganglion cell. 



IV. CARTILAGE. 



Dissect out the tip of the delicate xiphisternal cartilage of a 

 fresh frog, or slice a bit of the cartilage from the head of the femur 

 with a razor; mount in salt solution and study under the high 

 power. Note : ( I ) Large rounded cartilage cells scattered through 

 a nearly invisible and structureless matrix which forms a refractive 

 halo about each cell. (2) A distinct nucleus (or two) in each cell. 

 (3) After some time the cells contract and thus a space is formed 

 between the cell and the matrix. Draw. 



V. BONE. 



Examine with low power a section of bone (mammalian bone). 

 Observe : ( i ) Haversian canals, rounded spaces often filled with 

 air or dirt and then appearing black. (2) Lamellae, concentric lay- 

 ers about each haversian canal. (3) Lacunae, oval black spaces be- 



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