Volumetric Study of Hypophysis Cerebri. 419 



which together will constitute a more complete set consisting of 

 every tenth section and also to have a better nuclear stain. Every 

 section of one of these series only (as a rule) is projected at a mag- 

 nification of twenty diameters upon "American Linen Record" 

 paper (sheets 23 X 36 inches, 72 lbs. per ream) which runs very 

 uniformly at .012 gram per sq. cm. Every sheet needs checking 

 up, however. This is done by cutting out from each corner a 

 square 5 cm. each way and weighing the four squares together. 

 If a heavy sheet is balanced with a light sheet (several sheets being 

 necessary for each determination) the weight per sq. cm. can be 

 kept sufficiently constant. The capsule (including the connective 

 tissue extending in between the lobes), pars anterior, connective 

 tissue trabecular and large colloid masses in pars anterior, par- 

 enchyma of pars intermedia, colloid in pars intermedia, and pars 

 nervosa are outlined with a hard sharp pencil or with ink. Where 

 the colloid and parenchyma of pars intermedia are very irregu- 

 larly distributed, it is safer to use both series, thus reducing the 

 error greatly. 



These areas are cut out with scissors, using a fine manicuring 

 scissors for cutting out the smaller areas and areas rounded by 

 many sharp turns. The paper representing any particular part 

 is weighed. The percentage that this weight is of the weight of 

 the paper of all parts together constitutes the percentage of the 

 whole organ represented by that part, if the shrinkage is the same 

 for all parts in any particular case. 



To determine the shrinkage of the two lobes, they were separ- 

 ated from each other in three cases and each lobe weighed before 

 fixation. The members of each pair were kept together through 

 the entire process of fixation, embedding, etc. From serial sec- 

 tions, as explained above, the final volume was obtained by divi- 

 ding the total paper weight of a lobe by the weight of one sq. cm. 

 of paper, then dividing the results by the actual magnification 

 (magnification in diameter squared) and finally multiplying by 

 200 ix (20 X 10 aO reduced to cm. (.02 cm.). The original volume 

 (before fixation) was determined by dividing the weight by the 

 specific gravity. 



The results are tabulated in Table I, from which it is seen that 

 there is sufficiently close agreement between the shrinkage of the 



