186 THE MICROSCOPIST. 



From these elements result the simple and compound 

 tissues. 



The Simple Tissues may be divided into 



1. Cells with intermediate fluid, as Blood, Lymph, 

 Chyle, Mucus, and Pus. 



2. Epithelium and its appendages. 



3. Connective Substances. Cartilage. Fat. Connec- 

 tive tissue. Bone. Dentine. 



The Compound Tissues are Muscle, Nerve, Gland, and 

 Vascular tissues. 



These are formed into Organs. 



1. Vegetative. The Circulatory, Respiratory, Diges- 

 tive, Urinary, and Generative organs. 



2. Animal. The Bony, Muscular, Nervous, and Sensory 

 apparatus. 



We shall attempt a brief description of these tissues 

 and organs, as illustrated by the microscope and modern 

 methods of research. 



I. SIMPLE TISSUES. 

 1. CELLS WITH INTERMEDIATE FLUID. 



I. The Blood. 



The microscope shows blood to consist, especially in 

 man and the higher animals, of red corpuscles, colorless 

 corpuscles, and the fluid in which they are suspended. 



1. Blood Plasma, or Liquor Sanguinis. This is a color- 

 less and apparently structureless fluid, but when removed 

 from the body, fibrin separates from it in solid form. In 

 small quantities of blood this is seen in delicate fibres 

 crossing each other at various angles. 



2. Red-Uood Corpuscles. These were first discovered by 

 Svvammerdam, in 1658, in frog's blood, and in that of man 

 by Lewenhoek, in 1673. Malpighi is said to have first 

 seen the actual circulation of blood in the web of a frog's 



