207 



dition is of course far from the natural. The cells are obser- 

 ved in solutions which may be called protective, but do 

 not contain any nutriment lor the cells. Many dej^cnerative 

 phenomena will therclore he intei'preted wrongly. 



The architecture of the tissue cells in general has been 

 studied in vitro, under normal and pathological conditions. 

 Within the last few years mitochondrial structures of the 

 cytoplasm have been investigated specially. Lewis and 

 Lewis have developed a beautiful technique and thereby 

 contributed particularly to the study of the mitochondrial 

 apparatus. 



W. H. L e w i s ^'^'') has investigated the intimate struc- 

 tures of the fibroblasts ^eo a^^ endothelial cells ■^'^^ ') and epi- 

 thelial cells ^^53). 



In his excellent work on the cytoplasmic structures, 

 W. H. Lewis concludes, that the tissue cultures afford an 

 extremely good method for observations upon the undis- 

 turbed cells as they live. He finds mitochondria in all the 

 cells and they can be studied in the living unstained cell 

 for hours. The mitochondria may be scattered throughout 

 tiu' cytojjlasm or they may be located around the nucleus. 

 They change their position all the lime. During mitosis the 

 mitochondria become more evenly scattered throughout the 

 cytoplasm, except in the spindle area, where they are 

 usuallj^ absent. — All shapes of granules can be found, and 

 any one type of mitochondria such as granule, rod or 

 thread maj' at times change into other type or may fuse 

 with another mitochondrium — or again it may divide into 

 one or several mitochondria. They may change their shape 

 according to the experimental conditions. They may vary 

 from minute granules, short rods to long threads. The num- 

 ber of mitochondria in a single cell vary from two or three 

 to more than two hundred. The number of mitochondria is 

 not constant for the same kind of cell. If the mitochondria 

 degenerate, the rods or threads fall apart to granules — later 

 these granules become vesicles and then separate as a num- 



