QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 189 
Besides this it is in communication with the pineal gland 
and the ‘ ganglion habenule.’ 
Dr. Paulowsky made his observations on preparations from 
man, sheep, dogs, and rabbits. He arrives at the following 
conclusions : 
1. The so-called posterior commisure consists of coarse 
fibres running down from the brain to the tegmentum of the 
crus cerebri. 
2. These fibres have a four-fold origin— 
(a) In the pineal gland ; 
(3) In the frontal lobe of the brain (through the auterior 
peduncle of the thalamus) ; 
(y) In the temporal lobe and in the fissure of Sylvius 
(through the inferior peduncle) ; and 
(6) Probably in the thalamus itself. 
3. In the tegmentum one portion of the bundle of fibres 
runs with the ‘‘ Schleife,”? while another lies to the inner side 
of the same. 
4. Commissural, or bridge-like fibres, do not exist at all 
in the posterior commissure. 
5. Therefore the term “ commissura posterior” is an in- 
correct one, and it would be more advisable to call this region 
of the brain the crossed tract of the tegmentum—“ tractus 
cruciatus tegmenti.” (Medical Record.) 
2. Course of Fibres in the Spinal Cord.—Schieffer- 
decker (‘ Arch. fir Mik. Anat., vol. x, p. 471, plates 
32, 33, 34) has studied this subject by horizontal and 
longitudinal sections of the spinal cord of a dog in the lumbar 
enlargement at the level of the Ist and 2nd sacral nerves. 
The cord was hardened four weeks in Miiller’s fluid, then 
preserved in alcohol. The sections were made with a small 
microtome, and tinted with chloride of gold (longitudinal 
sections), or chloride of palladium (transverse sections), and 
finally mounted in Canada balsam. The strength of the 
tinting solutions was about | to 10,000. In one instance at 
least, the direct prolongation of axial processes of a ganglionic 
cell into the anterior roots of a spinal nerve was observed. 
The general principle of distribution of the fibres in the 
cord is according to the author, simply that of the utmost 
possible mutual connection, as shown in the following ar- 
rangement: 
(1) Passage of fibres from the white into the gray substance 
occurs in three modes :—(a@) Fibres starting from the same 
point enter the gray substance at different levels ; (2) Fibres 
coursing through different portions of the white substance 
may enter the gray substance at the same point; (c) Fibres 
b) 
