PRENATAL GROWTH OF THE PIG 115 



The following notes apply to the preceding table. The sex 

 was undetermined in litters 13, 14, and 24. The intestinal and 

 stomach contents were too small for measurement in the earlier 

 stages. In a few of the individuals in litters 5, 16, 23, 4, 3, 1, 

 47, 11, 10, 19, 9 and 20, and in three of the adults, the weight of 

 the contents is estimated. 



In a few other instances, the number of observations on indi- 

 vidual organs is less than the number used of the litter. Thus, in 

 litter 14, only two observations were made on the lungs, two on 

 spinal cord, and three on stomach and intestines. In litter 8, 

 only three observations were made on the thymus, and in litter 

 5, there were seven observations on thymus, and six on eyeballs. 

 Litter 23 contains eight observations on eyeballs; litter 4, only one 

 spinal cord. In the adult, only one observation each was made 

 on the brain, eyeballs and thyroid gland; two on pancreas and 

 suprarenals, and three on kidneys. The crown-rump length was 

 measured on only one (the largest) adult. 



From the averages of the various litters, curves of relative 

 growth for the different organs were constructed. The percent- 

 age which the various organs form of the entire (net) body weight 

 is used for the ordinate, and the average crown-rump length for 

 the abscissa. For convenience in drawing these curves, certam 

 of the litters of nearly the same size were grouped together and 

 their averages taken. Thus, litters nos. 17 and 21 were grouped 

 together at an average of 39 mm. ; nos. 2 and 5 at 84 mm. ; nos. 

 16, 23 and 4 at 107 mm.; nos. 3, 18 and 1 at 130 mm.; and nos. 

 47, 11 and 48 at 157 mm. The resulting curves are not essen- 

 tially different from those in which all the litters were used 

 individually, and the simplification due to the elimination of 

 occasional irregularities is an advantage, particularly when sev- 

 eral curves are combined in the same figure. 



The dotted portion of the line at the right indicates the trend 

 of postnatal relative growth, from birth to maturity. It must, 

 of course, be borne in mind that these curves give an idea only of 

 the general changes in the relative size of the various organs, and 

 no information concerning the age, or the rapidity with which the 

 changes occur. 



