VI RECORDING GROWTH AND BEHAVIOUR OF CELLS 579 



(Lewis, 1931b; 1936-37; 1937) from a study of moving pictures and named 

 "pinocytosis". 



Comparison of tumours with normal cells in moving pictures has been a fruitful 

 field. Among those who studied the movements and the mode and rate of prolifera- 

 tion of normal and neoplastic cells, and made observations which are important 

 for the differential diagnosis of certain types of tumour, especially those of the 

 nervous system, have been Canti (1932); Lewis and Lewis (1933); Bland, Russell 

 and Canti (1936-37); Bland and Russell (1938); Lewis (1948, 1950); Pomerat 

 (195 1, 1952); Costero^^ al. (1955a, b). Gey, Gey, Firor and Self (1949) and Gey, 

 Bang and Gey (1954) besides making such comparisons, also studied cells which 

 underwent a transformation in vitro from normal to neoplastic. 



The growth and organization of capillaries and endothelium in explants from 

 subcutaneous tissue of seven-day chick embryos was observed in films by Lewis 

 (1931a, 1941a). Similarly, organized growth in rudiments of limb (Canti and 

 Fell, 1933a, b; Fell and Canti, 1934) and sternum (Fell, 1936-37) has been 

 continuously recorded in moving pictures. 



Movements of parts of cells have been followed in films, e.g. cilia (Danes, 1949a, 

 b) ; mitochondria (Frederic, 1950, 1951; Chevremont and Frederic, 1951; 

 Frederic and Chevremont, 1952; Frederic, 1952, 1954a); pulsatile activity in 

 oligodendroglia (Canti, Bland and Russell, 1935; Pomerat, 1951; Lumsden and 

 Pomerat, 1951); and rotation of nuclei (Lewis, 1937; Pomerat, 1953a, b). Some 

 of these types of movement have been the subjects of quantitative measurements, 

 e.g. the rate of contraction of the oligodendroglia is about i contraction/5 min., 

 and nuclear rotations in human nasal mucosa take an average of 280 sec. per 

 revolution, the fastest rotation seen being one which was complete in 75 sec. 



Numerous studies have been made, with various refinements in technique such 

 as the introduction of dark-ground (Lewis, 1923; Carrel and Ebeling, 1926; 

 Strangeways and Canti, 1926, 1927-28; Canti, 1929) and phase-contrast illumi- 

 nation (Gey, Gey, Firor and Self, 1949; Hughes and Swann, 1948; Lewis, Pomerat 

 and Ezell, 1949) upon the mitotic process and other intracellular events (Pomerat, 

 Lefeber and Smith, 1954). Some of the finest films, however, were made with 

 direct illumination by Lewis (1930, 1931a, b, 1936-37, 1940, 1941a, b, 1948). 

 Careful studies have been undertaken to elucidate the length of each phase of the 

 mitotic cycle in both normal and tumour cells (Lewis and Lewis, 1933; Lewis, 

 1939). The different phases of mitosis in chick embryo fibroblasts were found to 

 vary considerably in different cells observed. Prophase, which is hard to recognize 

 (even with phase contrast, which Lewis did not have) lasts about 30-60 min. ; 

 metaphase 1-15 min. (average 3 min.); anaphase 2-3 min. and telophase 1-2 

 min. According to Lewis, fibroblasts from adult rat and mouse take about twice 

 as long in metaphase, anaphase and telophase as the embryonic chick cells, and 

 malignant fibroblasts twice as long as the normal adult rodent cells. Exact timing 

 is complicated by the difficulty in deciding, even in normal cells, just when pro- 

 phase begins. Some malignant cells have nuclei which, in interphase, look like 

 normal prophases (Lewis and Lewis, 1941b). Extensive studies, with the aid of 

 phase contrast, have been made by Hughes (Hughes and Preston, 1948; Fell and 

 Hughes, 1949; Hughes and Swann, 1949; Hughes, 1952). His data on chick cells 



Literature p. 581 



