CELLS AND TISSUES 



15 



tation is fulfilled in the results of experiments which have shown that 

 many tissues and cells of higher organisms may, if given structural 

 independence and a proper environment, continue to live or even in 

 many cases to grow into a complete new body. The ability of such an 





/ E 



Fig. 10. — A, reticular connective tissue from lymph gland of cat. {After Heidenhain.) 

 B, young heart muscle of dog embryo, showing myofibrils developing, but no subdivision 

 into cells. C, later stage of same. {B and C after Godlewski.) D, development of cells in 

 Plasmodium by vacuole formation in human embryonic epithelium. {After M archand.) 

 E, development of cartilage tissue from Plasmodium in Lophius. {After Studnicka.) 



isolated part to reconstitute a whole depends upon the measure in which 

 it has retained what is fundamental in the physico-chemical constitution 

 of protoplasts through the period of its differentiation. 



Correlation. — No such degree of differentiation and specialization 

 of tissues as we see in organisms could be attained, and no such complex 

 mechanism could continue to act as a unit or individual, were it not for 



