i6o 



GROWTH PRINCIPLES AND THEORY 



l(f 



10 



20 



30 40 5060 80 100 150 200 g 

 Wt. of ventricle 



Fig. 4. Allometric growth of heart muscle fibres in man. With increasing ventricle weight, 



fibre volume increases isometrically (a « i), nuclear volume linearly (with the cubic root of 



ventricle volume, a * 0.3), the nucleocytoplasmic ratio is surface-proportional (a « 0.7). 



o left, • right ventricle. After Linzbach, 1950. 



as to whether or not mitosis can be carried through under anaerobic conditions, 

 depending on the species concerned and its particular adaptive conditions. The 

 increase of respiration during mitosis is small and has a maximum in metaphase 

 and early anaphase, whereas cell division coincides with decreased respiration 

 (review in Bullough, 1952). In adult epidermis, mitosis is connected with the 

 Krebs cycle; hence it takes place only under aerobic conditions and if glucose or 

 the metabolites of the Krebs cycle are provided. Supply of glucose is necessary 

 in the antephase which, in various respects, appears to be a decisive phase in 

 mitosis (Bullough, 1952). In other tissues such as the embryonic brain of chicken 

 aerobic glycolysis appears to be the energy-yielding process. During the decrease 

 of mitotic rate in the third to the eighth day of development, there is no change 

 of respiration but decrease of glycolysis. Block of glycolysis by Na-fluoride and 



