108 LAWSON G. LOWREY 



For the ovum, some fifty adult ovaries were examined fresh, 

 by opening the large follicles under a dissecting microscope. 

 The ovum (including zona pellucida) was measured with an eye- 

 piece micrometer, whose divisions had a known value. The 

 largest ovum found is considered nearly, if not quite, the size of 

 the mature ovum. No data were found in the literature as to 

 the size of the mature ovum of the pig. 



Of the fetal material secured, the litter at 15 mm. was the small- 

 est which could be conveniently dissected and weighed. The 

 largest litter examined averages 262 mm. in crown-rump length, 

 and is not quite full term. However, the changes between this 

 stage and birth are probably slight, except in the matter of abso- 

 lute weight. That is, the relative size of the various organs would 

 probably not change much, since the changes are relatively slight 

 during the latter part of the fetal period. 



For the data on the adult, a trip was made to the local (Colum- 

 bia) packing house, and four hogs, probably about ten to twelve 

 months old, were examined and weighed. The individual meas- 

 ul-ements so secured were averaged, and the averages used in 

 constructing the various curves. 



The method used for the fetal and adult material was that of 

 weighing. The crown-rump length was also taken in all cases, 

 as it forms another basis of comparison for the individuals and 

 the different stages. 



Each litter is considered as a unit. That is, the individuals 

 in each litter, or the three or four average pigs which were used 

 therefrom, were weighed individually and individual calcula- 

 tions made for the percentage which each organ forms of the whole. 

 Where the intestinal contents were determined (186 mm. and 

 above), their weight was subtracted from the gross body weight, 

 giving the net body weight, which was used in calculating the 

 percentages. The average of the percentages for each organ is 

 then taken for the litter, and this average is used in the table of 

 observations, the minimum and maximum percentages observed 

 in the litter being also indicated in parenthesis. In constructing 

 the various curves of relative growth, it was found convenient 

 to group together certain of the litters closely related in size, the 

 average of the litter averages being taken. 



