258 THE BIOLOGY OF THE ANIMAL 



Microscopic Anatomy. 



From the freshly killed frog and in the man- 

 ner described the student will make and study- 

 preparations of the various parts named hereafter. 

 These are such as may readily be made on a glass 

 slide without elaborate manipulation. As only a 

 few structures can be studied in this way, he 

 should also have for examination a set of perma- 

 nent preparations of various organs which have 

 been hardened, stained, sectioned on a microtome, 

 and mounted in Canada balsam. This material 

 will be provided by the instructor, as the student 

 has not yet had sufficient training in histological 

 technique to enable him to prepare satisfactory 

 specimens. Before staining a preparation always 

 examine it in the fresh state in a drop of water 

 or of normal salt solution. Make drawings and 

 full notes of every specimen studied. 



a. The skin. 



Eemove pieces of skin from the various places 

 on the dorsal and ventral surfaces of the body 

 and from the limbs, mount in a drop of water, 

 and look for the pigment cells and the open- 

 ings of the cutaneous glands. 



1). The Hood. — See page 23. 



c. Connective tissue. 



1. Fibrous tissue.- — Tease a bit of the tendo 

 Achillis in water. Note the arrangement and 

 structure of the white, non - elastic fibres. 

 Do they branch ? Applj^ a drop of dilute acetic 

 acid. Look in this tendon and in those from 

 other parts of the body for yellow, elastic 



