62 STUDIES ON ALKALINE PHOSPHATASE 



a phosphokinase in the conservation of phosphate bond energy. 

 If gene products must be dephosphorylated to release the prod- 

 uct of the gene in active form, a considerable economy of the 

 energy of the phosphate bond would be effected if, instead of hy- 

 drolyzing the phosphate bond, the phosphate were transferred to 

 some other molecule: alkaline phosphatase could act as a catalyst 

 for such transfers. 



It should, of course, be clear from what has been said above 

 that we cannot at present do more than speculate about the 

 function of alkaline phosphatase in the cell nuclei. There must 

 also be considerable doubt as to whether it is at present profitable 

 to speculate about this matter at all. At present we can deter- 

 mine the cytochemical localization of very few substances in the 

 cell. In the nucleus we can determine pentose and deoxypen- 

 tose nucleic acids and alkaline phosphatase with some degree of 

 accuracy. But we can be reasonably confident that there are a 

 vast number of other substances present in the nucleus. Until 

 we know more about these other substances, only by the greatest 

 of good fortune can any of our speculations concerning the func- 

 tions of phosphatase and nucleic acid be correct. 



Phosphatase in the Nuclei of Ciliates 



Dr. H. Mugard has studied a considerable variety of ciliates, 

 using the alkaline phosphatase technique. The results may be 

 exemplified by considering the two species, Ophryoglena atra 

 and Opalina ranarum Stokes. With Ophryoglena no phosphatase 

 is found in the starved animals. Immediately after the taking 

 of food, phosphatase appears in the vicinity of the food vacuoles: 

 this occurs within a few seconds of formation of the vacuoles. 

 Very shortly afterwards phosphatase may also be observed in 

 the macronucleus, micronucleus, and throughout the cytoplasm. 

 Feeding is commonly followed by encystment. Following encyst- 

 ment the concentration of phosphatase falls in the cytoplasm, 

 and the macronucleus becomes negative. The micronucleus con- 

 tinues strongly positive. But as divisions proceed within the 

 cyst the amount of phosphatase in the micronucleus appears to 

 diminish at every division. 



With Opalina there is no phosphatase to be found in the cyto- 

 plasm unless division is occurring. The nuclei contain a con- 

 siderable amount of phosphatase, particularly in the chromo- 



