240 JOHNSTON. [VOL. I. 



(5) The anterior commissure is made-up chiefly of ascending 

 fibers which cross to end in the epistriatum of the opposite 

 side. In addition to these are the somewhat doubtful associa- 

 tional fibers of the cortical area, crossing likewise to terminate 

 in the epistriatum. 



Summary of Results. 



A. The olfactory lobe: 



(1) In addition to mitral cells of two sorts, six other forms of 

 cells, concerned in receiving and transmitting olfactory im- 

 pulses, are found in the olfactory lobe. 



(2) The granule cells are provided with axis cylinders and 

 glomerular dendrites, and are therefore nerve cells. 



(3) The olfactory lobe contains cells which are morphologi- 

 cally identical with the cells of Cajal. 



(4) The glomerular zone of the olfactory lobe contains cells 

 with short axis cylinders (associational cells). 



(5) The large mitral cells are provided with non-glomerular 

 dendrites. 



B. The fore-brain: 



(6) There is in the dorso-median region of the fore-brain a 

 large incompletely differentiated nucleus of cells with short 

 axis cylinders, constituting an imperfect epistriatum. 



(7) A group of cells is found on the lateral surface of the 

 fore-brain which agrees in position and apparently also in con- 

 nections with the cortex lateralis of Reptilia. 



(8) The cortical region of the fore-brain is connected with 

 the ganglion habenulae by a tractus cortico-habenularis. A 

 tractus olfacto-habenularis is also present. 



C. The habenular tracts: 



(9) Meynert's bundles do not end in the corpus interpedun- 

 culare, but undergo partial decussation there and pass on 

 toward the medulla. 



ZOOLOGICAL LABORATORY, UNIVERSITY OF MICHIGAN, 

 ANN ARBOR, MICHIGAN, September 24, 1897. 



