WEIGHT OF CRANIUM 



195 



The fact that these bones continue to increase in length nearly 

 as long as the rat lives, implies a condition which makes possible 

 this contmued growth, as shown in table 131. 



Table 132 gives the data by which determinations ot length 

 in any of the three states can be transformed. 



TABLE 132 

 Percentage losses in the length of long bones on drying. 



100 grams in body weight 



Mean values for rats above 



AMOUNT OP CHANGE 



Fresh to room dried: loss 



Room dried to oven dried: loss 

 Fresh to oven dried: loss 



AVERAGE PERCENTAGE LOSS IN LENGTH 

 ON DRYING 



Humer- ^j^^^^ Radius Femur Tibia 



per cent 



0.6 

 0.3 

 0.9 



■per cent 



0.4 

 0.2 

 0.6 



per cent 

 0.4 

 0.2 

 0.6 



per cent 



0.7 

 0.3 

 1.0 



per cent 



0.5 

 0.2 



0.7 



TABLE 133 

 The mean iveight in grams of the crania in each body weight group of the four series 

 of albino rats from Paris, London, Philadelphia, \ ienna {based on table 4, 

 Donaldson '12 a). Each weight group is based on six cases, three males and 

 three females. 



For the corresponding weights of the Norway crania see table 191. 



(c) Weight of cranium. Determinations of the weight of the 

 cranium dried at room temperature have been made, Donaldson 

 ('12 a). By the cranium is meant the skull with upper teeth, 

 minus the mandible with lower teeth and minus the ear bones. 

 The mean weights are given in table 133. These crania were 

 preserved originally in weak alcohol. 



