112 KANSAS UNIVERSITY SCIENCE BULLETIN. 



of tympanum, 4.75 mm. From posterior end of tympanum to 

 anterior end of shoulder, 2.25 mm. From anterior end of 

 shoulder to anus, 7.50 mm. From anus to tip of tail, 13.50 mm. 



The embryo had been fixed in picro-acetic acid and the sec- 

 tions stained with Mallory's triple connective tissue stain 

 which brought out the brain and nerves as purple against the 

 red, orange and blue of the other tissues. 



The model was constructed according to the directions of 

 Karl Peter in his "die Methoden der Rekonstruktion." The 

 method is briefly as follows: Projections are made of each 

 consecutive section by means of the stereoscope and outline 

 drawings made of the parts to be reconstructed. The mag- 

 nification is governed by the distance between the stereoscope 

 and the screen upon which the drawings are made. In this 

 particular piece of work a magnification of fifty diameters 

 was used. Wax plates are next prepared, the drawings being 

 fixed to them while the wax is still hot. The proper thickness 

 of the plates is obtained by multiplying the actual length of 

 the object to be reconstructed by the magnification and divid- 

 ing the result by the number of sections contained in the 

 series. Brass strips of the correct thickness are placed upon 

 a smooth surface, the liquid wax poured upon the surface be- 

 tween them and a hot roller applied to the cooling wax, which 

 is pressed out to the thickness of the strips. The plates are 

 then cut along the lines of the drawings and are placed upon 

 each other to form the model. In order to facilitate the build- 

 ing process a guide line is used. This line is introduced into 

 the paraffin block by painting with lampblack one surface 

 parallel to the object to be sectioned and recoating with a thin 

 coat of paraffin. Cross sections of the tissue will then contain 

 also cross sections of this painted surface in a constant relation 

 to the tissue. 



GENERAL TOPOGRAPHY OF BRAIN. 



The plates and their explanations illustrate nearly all the 

 points intended to be brought out, so the discussion of them 

 will be brief. The slender olfactory lobes (A) extend pos- 

 teriorly and unite with the larger cerebral lobes (B) by the 

 olfactory peduncle. 



Immediately beneath the cerebral lobes is the median optic 

 thalami (C). At the base of the anterior margin of the optic 

 thalami is the infundibulum (Inf), which appears as a small 



