360 Dr. F. H. Thiele. Efferent Relationship of Optic [Apr. 19, 
A small fertile pinna is given natural size at fig. 4, and the same specimen 
is enlarged two times at fig. 5, where the arrangement of the microsporangia 
is clearly exhibited. 
My thanks are due to Mr. H. W. Hughes, F.G.S., to whom I have been so 
often indebted in the past for assistance in my studies of the Carboniferous 
Flora, for the opportunity of describing these interesting specimens. 
On the Hfferent Relationship of the Optic Thalamus and Deiter’s 
Nucleus to the Spinal Cord, with special reference to the 
Cerebellar Influx Theory (Hughlings Jackson) and the 
Genesis of Decerebrate Rigidity (Sherrington). 
By F. H. Ture,z, M.D., B.Sc., M.R.C.P., Pathologist to University College 
Hospital. 
(Communicated by Sir Victor Horsley, F.R.S. From the Laboratory of Chemical 
Pathology, University College, London. Received April 19,—Read May 18, 
1905.) 
In the following experiments it was determined to re-investigate the 
matter of the thalamo-spinal mechanism from the point of view of tracing 
the relations of the thalamus to the mesencephalon and hind-brain. 
Now, the thalamic grey centres are in association with the bulb and cord 
by the thalamo-bulbar and spinal tracts, placed on and around which are the 
rubro-spinal, tecto-spinal, Deiter-spinal, and the lateral cerebello pontine 
tracts. As the pyramidal fibres run through the mesencephalon it became 
necessary to exclude them in arranging the investigation. 
The general methods employed were as follows :— 
A. The localisation of the genesis of decerebrate rigidity and the influence 
of the cerebellum were determined by making successive coronal sections 
through the thalamus, mesencephalon pons, and bulb. 
B. Excitation of the superior and middle cerebellar peduncles in normal 
animals and in others in which the pyramidal tracts had been previously 
degenerated by suitable lesions in the middle zone of the cerebral hemi- 
spheres. 
C. Excitation of the cut surface of the thalamus and mesencephalon with 
or without previous pyramidal degeneration. 
The experiments were all performed under complete anesthesia, the 
anesthetics used being chloroform or ether. In cases where the brain was 
