EFFECTS OF INANITION IN THE PREGNANT ALBINO RAT. 95 



Throughout the period of inanition the pregnant females were kept in a spe- 

 cially warmed room in order to prevent death from chilling or pneumonia. 



AUTOPSIES. 



In this investigation 99 rats were autopsied, GO of which were from mothers 

 underfed during the last half of pregnancy, 29 were normal fetuses removed from 

 the recently killed mother, and 10 were normal newborns. In order to compare the 

 effect of prenatal inanition in the newborn rat (test), it was necessary to compare 

 this test rat with a normal (control) fetus of the same body-weight from an un- 

 starved mother. 



The mothers from which the control fetuses were obtained were chloroformed. 

 After death the abdomen was slit open and the fetuses and placentae removed from 

 the uterine horns. The fetus was removed from the amniotic sac and the umbilical 

 cord severed by crushing in order to prevent bleeding, close to the belly wall. The 

 fetus was quickly wiped dry of excess fluid, killed by chloroform, measured, weighed, 

 and dissected. These are. designated the "prenatal controls." The "test rats" 

 are newborn rats from the underfed mothers. The "normal newborns" are new- 

 born rats from normal litters. 



The series and number of the mother, the number of the litter, and the order in 

 the litter for each individual dissected is shown in table 4. A or B with the number 

 following denote the series and number of the mother in the series; the number 

 following this denotes the number of litters the mother has borne during the ex- 

 periment, while the number following the decimal point denotes the number of the 

 individual rat in the litter. For example, B2-2.1 would show that the rat was 

 number 1 in the second litter from the mother number 2, Series B. 



It will be noted that these rats (table 4) are arranged in five groups in accord- 

 ance with their net body-weights. Group 1 contains the test rats and prenatal 

 controls whose net body-weights range from approximately 2 to 2.5 grams; Group 

 II, those ranging from 2.5 to 3 grams; Group III, those ranging from 3 to 3.5 grams; 

 Group IV, those ranging from 3.5 to 4 grams, and Group V, those ranging from 4 to 

 4.5 grams. This grouping was done in order to facilitate computations and t<> 

 render apparent any variations according to the size of the rats. Since no sexual 

 differences were found in the organs and parts, the sexes are combined in the groups 

 and -computations. All computations were made on the average weights of the 

 organs and parts. The original individual data will be filed at the Wistar Institute 

 of Anatomy, Philadelphia, where they will be available for reference. 



All the test rats autopsied were born by the natural method, although the 

 length of gestation was occasionally prolonged. 



The autopsy technique used was the same as that described by Jackson and 

 Lowery (1912) and Jackson (1913), with a few modifications. Their technique was 

 as follows: After killing with chloroform, the gross body-weight and lengths of 

 body (nose-anus) and tail were recorded. The head was removed on a plane just 

 anterior to the larnyx and posterior to the cranium, and weighed. The trunk was 



