18 



HITCHCOCK'S ANATOMY 



61. Shape of Cells.— 3. Cells. These aie merely mem- 

 branous bags, or vesicles, from ,2bth toWooth of an inch in 

 diameter, filled with some kind of liquid, or solid substance. 

 When free, the form is spherical, or spheroidal, as in Fig. 6. 

 But, as they press against one another, they are brought into 

 a polyhedral form, as in Fig. 7, showing a group of fat ve- 

 sicles. 



Fig. 6. Fig. 1. 



62. Contents of Cells; Granules; Nucleus and Nucleo- 

 lus. — The fluid of cells is transparent, except in the case of 

 blood. In it there generally float an immense number of gra- 

 nules, having no investing membrane, but sometimes they are 

 thus invested. Each cell has also a nucleus and a nucleolus ; 

 the first being a globular, or lenticular body, from ^ oVoth to 

 eVooth of an inch in diameter, attached to, or imbedded in the 

 wall of the cell, though some are free. The nucleolus is a 

 granule within the nucleus. Both are shown, as well as the 

 common granules, in Fig. 6. 



63. Appendages of Cells.— Sometimes cells have a sort of 

 tail attached to them, and are hence called caudate, as in 

 Fig. 8. Sometimes, too, they are stellate, as in Fig. 9, show- 

 ing the pigment cells of a frog's foot. 



61. Define cells. What is the originnl form of them? How do they acquire the poly- 

 hedral form? 62. Explain nucleus, nucleolus and cell wall. 63. What are the appendages 

 of cells? 



