AN IMPROVED JiIETHOD OF MODELING. 295 



tion individually, the sulci and gyri are worked out with the original 

 section as a model, the two adjacent sections being occasionally consulted 

 for their exact locations. Whenever the pulp dries too much it is 

 moistened with a diluted solution of gum arable. 



Painting the model. — To distinguish the white from the gray matter 

 and the different structures inside the brain from each other, water colors 

 are used for all biit the cortex, where oil is preferable. While the model 

 is drying the two outlined pieces of white paper corresponding to section 

 No. 2 are taken and with the original sections at hand the different 

 parts are painted with different colors, giving the same color to those 

 parts having the same or allied structure. 



Last step. — Wlien the model-sections are dried (which takes about one 

 week, or longer, according to the water contained in the pulp), the 

 white papers containing the copies of the surfaces of the sections are 

 pasted on them and the gap left around the border, due to a slight 

 contraction of the blotting paper, is filled up with pulp and left to dry. 

 Next, the cavity for the ventricles is excised, as this can not be done 

 when the pulp is moist, the newly exposed parts painted and after all 

 is completed the outside is painted with oil colors. The same procedure 

 is followed for the coronal sections and the sagittal and horizontal ones. 



The record book. — A record book should be kept in which the onion 

 skin papers containing the outlines of the internal structures should 

 be preserved and to each of these the corresponding name should be 

 given as their study is continued. 



Experiments. — With the hope of further im.proving brain modeling we 

 conducted some experiments the results of which are as follows : 



Newspaper, macerated for three days in water, and reduced to a fine 

 pulp of dark-gray color, has short fibers, but forms a soft mass easily 

 workable into any desired shape. Painted with oil colors, almost no 

 contraction occurs when dijing and sections can easily be reduced to 

 an 8 millimeter thickness. 



With one-half newspaper pulp and one-half lime a pulp is produced 

 that can be used to make sections 8 millimeters thick; this dries within 

 twenty-four hours into a hard, strong, white mass with an even surface, 

 which is easily painted. With gum the resulting mass is more i^lastic, 

 but dries less quickly. 



With one-third pulp, one-third lime and one-third sand, the mass 

 is dark and dries more quickl}^, but it is brittle and not adapted for 

 brain modeling. 



We repeated the above experiments with magazine paper and ordinary 

 white paper and obtained almost the same results. 



This method of modeling can obviously be used for other purposes 

 such as the reproduction of fruits, insect's, etc., so that it can be made 

 of advantage to botanists, zoologists, paleontologists, etc. 



