56 STUDIES ON ALKALINE PHOSPHATASE 



phibia (Danielli, unpublished) and fish tissues (Lorch, 1949), in 

 various invertebrate tissues (de Nicola, 1949; Danielli, 1950b), 

 and Mugard (1953) has found that in various Protozoa phos- 

 phatase is a common nuclear constituent. The nuclear phos- 

 phatase of Protozoa is often distributed in a manner similar to 

 the distribution of deoxyribose nucleic acid, as demonstrated by 

 the Feulgen reaction, but undergoes considerable quantitative 

 changes during the various phases of the life history of the 

 Protozoa concerned. 



Alkaline phosphatase is also commonly found in tumors. 

 Plate VII, Fig. D, shows the distribution of phosphatase in a sec- 

 tion of Walker rat sarcoma. Here again the distribution of alka- 

 line phosphatase tends to follow that of the Feulgen positive 

 material on the chromosomes but differs from the Feulgen posi- 

 tive material in being present in very high concentration in the 

 nucleolus. 



When tumor tissues are treated with mitotic poisons, there is 

 again a general tendency for the Feulgen reaction and for the 

 distribution of phosphatase to be similar, except so far as the 

 nucleolus is concerned. Plate VIII shows in Fig. A the distribu- 

 tion of Feulgen-positive material and in Fig. B the distribution 

 of alkaline phosphatase, in both cases in cells in which the mitotic 

 poison has prevented spindle formation, so that when the nuclear 

 membrane broke down the metaphase chromosomes have been 

 distributed throughout the cell. This abnormal behaviour of the 

 chromosomes is frequently followed by pycnotic degeneration, 

 and often at this stage there is a marked parallelism between the 

 Feulgen reaction and the phosphatase distribution, as may be 

 seen from Figs. C and D on the same plate. 



The marked tendency for alkaline phosphatase to follow the 

 •distribution of Feulgen-positive material can hardly be devoid 

 of significance. Although the occurrence of alkaline phosphatase 

 in the nucleolus is an exception to this general rule, it must be 

 remembered that the nucleolus is a site of high concentration of 

 pentose nucleic acid. Interest in this parallelism has led Danielli 

 and Catcheside in 1945 and Krugelis in 1945 to study the distri- 

 bution of alkaline phosphatase on the polytene chromosomes of 

 Drosophila salivary gland nuclei. When salivary glands are sec- 

 tioned after fixation with alcohol, it is easy to demonstrate that 

 the nuclei contain considerable amounts of alkaline phosphatase, 



