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XXXI.—Scottish National Antarctic Expedition: A Contribution to the Histology 
of the Central Nervous System of the Weddell Seal (Leptonychotes weddellii). 
By Harold Axel Haig, M.B., B.S. (Lond.), M.R.C.S. (Eng.), L.R.C.P. (Lond.), 
Lecturer in Histology and Embryology, University College, Cardiff. Commumn- 
cated by Dr W. 8S. Brucz. (With Two Plates and Nine Text Figs.) 
(MS. received June 18, 1912. Read December 2, 1912. Issued separately February 17, 1913.) 
CONTENTS. 
Part I. | (f) The Cerebellum. 
(a) The Spinal Cord. | (g) The Optic Thalamus. 
(b) The Medulla Oblongata. 
(c) The Pons Varollii. 
(d) The Mesencephalon. a 1, 
(e) The Motor Cortical Area. The Pituitary Gland. 
PARE +f. 
INTRODUCTORY AND PractTIcAL DETAILS. 
The specimens submitted for examination were : 
(a) Portions of the brain (labelled Specimen XXX1.). 
(b) Portions of spinal cord (labelled Specimen XXIV.). 
Both were in excellent condition as regards fixation and hardening, having been 
preserved for many years in a fluid composed of formol and 95 per cent. alcohol (the 
fluid was also injected into the cerebral vessels). They were, previous to histological 
examination, submitted to the following processes :— 
i. Comparatively thin slices were taken from various regions and placed for 
twenty-four hours in absolute alcohol. 
ii. Then transferred to acetone for twelve hours. 
iti. Placed in xylo] until permeated. 
iv. Embedded in paraftin of melting-point 52° C. Sections were then taken 
with an improved form of the Cambridge rocking microtome, and fixed to 
slides by means of the albumen method. 
Stavmng of the Sections. 
The best stain for differentiating the grey and white matter was found to be 
Weigert’s method with acid fuchsin, used alone, or subsequent to treatment with 
Delatield’s hematoxylin. Other stains were tried (Bismarck brown with acid fuchsin 
as counterstain, aniline blue-black, hematoxylin and orange-G., etc.), but acid-fuchsin 
TRANS. ROY. SOC. EDIN., VOL. XILVIIT. PART IV. (NO. 31). 125 
