EFFECTS OF INANITION IN THE PREGNANT ALBINO RAT. 127 



With but few exceptions, those organs which show the most marked gain in the 

 newborn rats (underfed from birth to 16 days) during postnatal inanition are also 

 above normal in prenatal inanition. The spinal cord is the only exception. Also, 

 all the organs which show a loss or only a slight gain in the newborn rats during 

 postnatal inanition (excepting the indefinite "remainder") are subnormal in weight 

 in prenatal inanition. 



It should be noted that the organs and systems that are above the normal 

 weight in prenatal inanition have apparently a lower growth capacity than that 

 shown in postnatal inanition just after birth (see table 6), while those organs and 

 systems which are below normal weight in prenatal inanition (with the exception of 

 the thymus) suffer a greater loss than in postnatal inanition. From the foregoing 

 it is evident in general that the organs and systems of the rat have a weaker growth 

 tendency during prenatal than during postnatal inanition. 



The present investigations, therefore, emphasize the fact that in different 

 periods in the life of the rat certain organs and parts react differently, as manifested 

 by their growth during inanition. This is probably due mainly to the varying 

 intensity of the normal growth tendency in the organs and parts at different periods. 



Jackson and Stewart (1918) have called attention to the fact that during in- 

 anition in the rat the varying intensity of growth tendency in the different organs 

 and systems depends on four factors: (1) the duration of the period of inanition, 

 (2) the age at which it occurs, (3) its severity, and (4) the character of the inanition. 



In prenatal inanition the duration is known (period of starvation of mother). 

 The age is known (length of gestation). The severity is apparently that sufficient 

 to retard the growth of the entire body, an average of 40 per cent as compared with 

 normal newborn controls. Attention may be called to the fact that some of the 

 apparent differences in the growth tendencies of the organs and parts during pre- 

 natal and postnatal inanition may be due to the difference in the relative retardation 

 of the body-growth. That is, while the body-growth (average) was retarded 40 per 

 cent in prenatal inanition, it was retarded 66 per cent in Stewart's (1918a) series in 

 starvation just after birth. The real nature of the inanition, i. c, the amount of 

 reduction in the various nutritive substances reaching the fetus during starvation of 

 the mother, is unknown. The exact character of the inanition to which the fetus is 

 subjected is, therefore, uncertain. However, from the nature of the changes in the 

 relative weight of the organs and parts, it may be stated that the maternal organism 

 during starvation in pregnancy makes extraordinary efforts, as is well known, to 

 keep up the necessary supplies of nutritive substances to the growing fetus and thus 

 protect it from the effects of inanition. 



SUMMARY. 



( 1 ) Starvation instituted shortly after copulation in the female albino rat appar- 

 ently results in an inhibition of pregnancy in the majority of cases. Whether this is 

 due to an inhibition of the implantation, or to death of the ovum, has not been proved. 



(2) Of 59 female albino rats starved from the eleventh day after copulation, 

 early death of the fetus in utero occurred in 3 cases. Microscopic examination of the 



