EFFECTS OF INANITION IN THE PREGNANT ALBINO RAT. 109 



weight of 0.871 gram, or 17.3 per cent of the body-weight, 5.03 grams. The visceral 

 group in my normal newborn series weighs 0.817 gram, or 16.6 per cent of the body- 

 weight, 4.92 grams. 



In my prenatal controls the weight of the visceral group forms 23, 21 , 18.5, 19.5, 

 and 19 per cent of the body-weight in Groups I to V, respectively (computed from 

 table 5) . Therefore it is evident that the relative weight of the visceral group in the 

 prenatal controls (fetuses) exceeds that of the normal newborn rat. This difference 

 is most marked in the smaller rats (fetuses), decreasing as the birth-weight is ap- 

 proached, showing that in the fetal life of the rat (from 2 to 4.1 grams) the viscera 

 constitute a larger proportion of the body-weight than at birth. 



In my test rats the weight of the visceral group forms 16.2, 16.6, 16.6, 16.2, and 

 15.2 per cent of the body-weight in Groups I to V, respectively (computed from table 

 5). Thus, in the test rats the visceral group forms a slightly smaller percentage of 

 the body-weight than in the normal newborn, while in the prenatal controls the con- 

 verse is true. The relative weight of the visceral group is markedly lower in the 

 test rats than in the prenatal controls. 



In my test rats the absolute weight of the visceral group is less than that of the 

 prenatal controls in all the groups (table 5) . In Groups I to V the absolute weight 

 of the visceral group in the test rats is 27, 21, 7, 17, and 20 per cent below that of the 

 prenatal controls in the corresponding groups, averaging 18.4 per cent below. 



Thus in prenatal inanition the visceral group shows a marked retardation in 

 growth. This is due chiefly to the retarded growth of the liver and lungs. 



These results are directly opposed to those in postnatal inanition shortly after 

 birth. Stewart (1918, 1918a) found that the absolute weight of the visceral group 

 exceeded that of controls of the same body by 46, 28, and 38 per cent in rats underfed 

 from birth to an average of 16 days, from birth to 3 weeks of age, and from birth to 

 10 weeks of age, respectively (table 6). In rats underfed from the age of 3 weeks 

 to 10 weeks and from the age of 3 weeks to 1 year, there was no marked change 

 in the weight of the visceral group (Jackson, 1915a; Stewart, 1918); while in rats 

 underfed from 10 weeks of age to 8 months, Jackson (1915a) found the weight of the 

 visceral group to be 12 per cent below the normal. He found that the visceral 

 group as a whole undergoes very little change in relative weight in adult rats during 

 either acute or chronic inanition. 



From the foregoing data it is evident that the growth tendency of the visceral 

 group in the rat during inanition is relatively weak before birth, strongest shortly 

 after birth, and decreases gradually thereafter. 



Remainder. — The "remainder" is obtained by subtracting the weight of the 

 integument, "moist" skeleton, musculature, and viscera from the net body-weight. 

 It thus includes the loss by evaporation of fluids which escape from the body during 

 dissection, also the larynx, trachea, esophagus, salivary and lymph glands, large 

 vessels, and pieces of fat in the omentum. The remainder may vary with the 

 amount of fat removed from different portions of the body. 



