MACERATION PROCEDURES 7 



cells in tissues cannot be studied readily. Then the methods of 

 manipulation are not devoid of action upon cell fractions which 

 are under study. For example, Shapiro found that when sea 

 urchin eggs are centrifuged, first so as to cause stratification 

 and then so as to cause the cell to divide into two halves — one 

 light and one heavy — the respiration of the two fragments so 

 formed is greater than that of the initial intact egg. It there- 

 fore follows that in an experiment of this type either there has 

 been a change in the physico-chemical organisation of the 

 enzyme systems of the cell, or else there has been synthetic ac- 

 tivity on the part of the cell, resulting in the formation of more 

 respiratory enzymes. Whichever of these changes may have 

 taken place, it is clear that the final condition, as revealed by 

 the cell fragments, cannot be taken as a close guide to what 

 was happening in the intact egg. In this connection, Holter re- 

 marks, "The only conclusions to be drawn from such experi- 

 ments are those based on the distributions of substances, • • • 

 [which] • • • permit, of course, only indirect conclusions with 

 regard to physiological activity." In any experiments involv- 

 ing the destruction of the known relationships between cellular 

 entities, as is the case in stratification, any deduction is dubious 

 unless it is established that the procedure does not lead to syn- 

 thesis or to destruction of chemical components. It is obligatory, 

 in such experiments to establish the lack of such synthesis or 

 degradation. 



Maceration Procedures 



Amongst the most common techniques employed today, par- 

 ticularly by biochemists seeking to make a contribution to 

 cytology, are techniques involving the disintegration of cells 

 into fragments, and fractionation of the fragments so formed. 

 The debris formed by maceration is commonly centrifuged at 

 various speeds so as to isolate fragments with different sedi- 

 mentation rates. It is hoped that methods of this type will 

 isolate granules, mitochondria, nuclei, and chromosomes, in a 

 condition which is closely similar to, if not identical with, the 

 state of those bodies in the intact cells. It would undoubtedly 

 be of the greatest value if it were true that cell organs could 

 be isolated in this way. But so far there has been an almost 



