312 HENRY H. DONALDSON 



It appears from this table that the loss in fresh weight drops 

 from about 16 per cent at birth to about 7.5 per cent at a body 

 weight of 100 grams, and after a body weight of 200 grams the 

 weight of the macerated may be below that of the unmacer- 

 ated bones — from 4.5 to 3.5 per cent. When, however, the oven- 

 dried weights of these same bones are compared, it is seen that 

 while the losses after oven-drying follow the same course as was 

 followed in the case of the fresh bones, yet the values run very 

 consistently — about 3 to 3.4 per cent (on the average) below 

 those for the fresh bones. 



EFFECT OF MACERATION IN 'GOLD DUST WASHING POWDER' ON 

 THE PERCENTAGE OF WATER IN THE OVEN-DRIED BONES 



Maceration reduces the weight of the moist (fresh) bones, as in 

 table 34 under 'fresh.' 



If this treatment merely dissolved some of the bone and left 

 the remainder unmodified in constitution and in water content, 

 then the bones oven-dried after maceration would have the same 

 percentage of water as those mechanically cleaned. The oven- 

 dried bones, however, show after maceration less water than those 

 mechanically cleaned. 



At birth the oven-dried macerated bones show 0.6 per cent 

 less water, and this deficiency increases at the rate of 0.04 per 

 cent for each 5 grams of body weight up to 150 grams. At this 

 body weight it amounts therefore to 1.8 per cent and the same 

 deficiency persists in the heavier rats. 



The complete explanation of these changes in weight and 

 water content as the result of maceration cannot at present be 

 given, but it appears that in general the young bones suffer 

 most in the destruction of their substance by the macerating 

 fluid, whereas with increasing age the reduction of the percentage 

 of water rises to about puberty, after which it remains nearly 

 constant. 



