Summary of the Frog 



119 



According to the structure of the composing cells, epithelial tissue 

 is known as : 



(a) Cuboidal, 



(b) Cylindrical, 



(c) Columnar, 



(d) Squamos, 



(e) Stratified. 



Connective Tissue is known as : 



(a) Cellular, when it is composed almost entirely of cells with 



little substance in between them. 



(b) Homogeneous, if the entire substance looks very much 



alike. 



(c) Fibrous, 



(d) Cartilage, 



(e) Bone. 



The Muscular Tissue is divided into : 



(a) Striated or Voluntary Muscles, 



(b) Non-striated or Involuntary Muscles, 



(c) Heart Muscle. 



The Nervous Tissue consists of cells known as : 



(a) Unipolar, 



(b) Bipolar, 



(c) Multipolar. 



Some writers call blood and lymph cells (Fig. 43) a fifth type of 

 tissue. 



Red Corpuscles (ery- 

 throcytes) ( " ) (caus- 

 ing the characteristic red color 

 of the blood) occur almost 

 only in vertebrates. (In in- 

 vertebrates, such as the earth- 

 worm, the blood-plasma is 

 red.) The red corpuscle has 

 no nucleus in the mammal 

 while in other vertebrates it 

 has. 



White Corpuscles (leu- 

 cocytes) ( ) are wan- 

 dering cells in the blood and 

 lymph, which are phagocytic 

 ( ) in their action, 

 that is, they assist in keeping 

 the body in health by devour- 

 ing foreign substances. 



Fig. 43. . 



A, Red blood corpuscles (haematids) of the 

 frog, stained with safranin and much magni- 

 fied, to show the nucleus and nuclear net- 

 work, bl, an amoeboid coarsely granular 

 leucocyte from the frog's blood, showing trifid 

 nucleus; b2, hi, b4, other forms of leucocyte 

 from the frog's blood. c, discoid non- 

 nucleated haematids from human blood, much 

 magnified; cl, c2, c3, different forms of leu- 

 cocytes from human blood. (After Bourne.) 



