Hehkick, Morpho/oi^v of Acrvo/zs Sysfcm. 2.^ 



tracts from the latter seem to be short superficial ventral 

 bundles, and, less certainly, a few median strands along the 

 longitudinal fissure. We have much evidence that a similar 

 condition prevails in mammals. The question also rises 

 whether the caudad praecommissural tract be not homologous 

 with the fornix. 



The connective elements of the cerebrum have been 

 variously interpreted, and chemical researches more refined 

 than now possible may be necessary to fully discriminate 

 the tissues. Our sections reveal two apparently distinct 

 systems. The framework consists of the epithelium of the 

 ventricles and their derivatives, the latter being in the form 

 of fibres extending to the periphery and bearing at intervals 

 fusiform inoblastic cells. The intervals left between these 

 fibres is filled with a material which after treatment with 

 acid and alcohol is reticular, and forms a mat or felt of great 

 uniformity supporting the cells. As to the normal condi- 

 tion of this stroma, two views are possible, either the 

 substance is composed ot a reticulum and a soluble or 

 coagulable filling, or the reticular appearance is artificial and 

 the result of the partial solution and partial coagulation of 

 what was originally a gelatinous and homogeneous mass. 

 The latter view seems the more probable. Aside from the 

 nerve cells, nutritive bodies having the appearance of mi- 

 grant blood corpuscles are scattered in the stroma. These 

 have only the nucleus colored, while the body is either dis- 

 solved or entirely transparent. 



There is no marked difference in structure between the 

 connective tissue of the cerebrum and that of the rest of the 

 brain. 



The Diencephalon. — The habena in the lizard forms a 

 considerable cephalo-dorsal protuberance, consisting of two 

 closely-packed cell-masses on either side of the cylindrical 

 crus of the epiphysis. The two portions are connected by a 

 small but distinct commisural band, which may be termed 

 commissura habenaria. In the habena itself there are, in 



