392 ANATOMICAL AND PATHOLOGICAL OBSERVATIONS. 



surfaces of parts or organs. One surface of the membrane 

 is therefore attached, and is applied upon a layer of areolar 

 texture, intermixed with a more or less rich network of 

 capillary vessels. The other surface is free, and it is on it 

 only that the developed or secondary cells of its germinal 

 spots are attached. These secondary cells are at first con- 

 tained between the two layers of the membrane, these layers 

 being the opposite walls of each of its component cells. 

 When fully developed, the secondary cells carry forward the 

 anterior layer, which is always the thinnest, leaving the 

 nuclei or germinal centres in the substance of the posterior 

 layer in close contact with the bloodvessels. 



Of the forces which exist in connection with centres of 

 nutrition, nothing very definite can yet be stated. When this 

 branch of inquiry shall have been opened up, we shall expect 

 to have a science of organic forces, bearing direct relations to 

 anatomy, the science of organic forms. 



