oe wr: 
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————— ss 
Janvary 20, 1923] 
there have been two leading theories of nerve structure. 
According to the older, nerves are formed by chains of 
cells the protoplasm of which becomes differentiated 
‘in place into nervous fibrils. According to the newer 
and almost universally accepted view, first firmly 
established by Ramon y Cajal, the nerve fibre or axon 
throughout all its length is the outgrowth of a single 
cell, the neurone or neuroblast. When it is cut the 
distal portion of the fibre, being separated from the 
influence of the nucleus contained in the neuroblast, 
undergoes ‘“‘ Wallerian” degeneration: the proximal 
stump grows out again into the old sheath, and so the 
fibre is regenerated. According to Nageotte, both 
theories are true. The axon, or, as he terms it, the 
“neurite,” is the outgrowth of the neuron, but it can 
only grow along chains of ectoderm cells which con- 
stitute the sheath of Schwann. The only exception to 
this rule is when the axon reaches the ectoderm itself ; 
in this medium it grows as a “naked” fibre. The 
medullary sheath belongs to the axon itself; it is pro- 
duced by the confluence of mitochondria, and it is 
broken up and absorbed when the axon degenerates. 
When a nerve has been cut and the axons have de- 
generated, there ensues a rapid proliferation of the bands 
of ectoderm cells both at the proximal and distal sides 
of the cut: these bands form networks, and both cut 
ends may assume the aspects of swollen knobs. The 
upper of these is termed by Nageotte the “ neurome,” 
the lower the “ gliome.’”’ The neurome becomes in- 
vaded by new axons; many of these get into lateral 
branches of the ectodermal network and never reach 
their destinations, but when neurome and gliome meet, 
as they eventually do, some axons penetrate the lower 
part of the nerve and so function is restored. 
Nageotte has also established the remarkable fact 
that if a piece of a nerve be cut out and employed as a 
subcutaneous graft it becomes the centre of a nodule of 
firm, tough connective tissue, evidently showing that the 
cells of Schwann emit some substance which acts as a 
stimulus to the production of this kind of tissue. For 
this reason, when a long portion of a nerve has been lost 
and a graft is necessary to restore continuity, a graft of 
dead artery or tendon is often more effective than one 
of dead nerve. 
The outstanding result of Nageotte’s researches seems 
to us to be that the connective tissue cells have the 
power of acting as bone-cells, cartilaginous cells, “ fibro- 
blasts,” or even smooth muscle fibres, according to the 
circumstances in which they are placed; that in 
Driesch’s words the prospective fate of a cell is deter- 
_ mined not by its nature but by its position —that 
“Ein jedes jedes kann” and this is a vitalistic con- 
ception, not a chemical or physical one. 
E. W. MacBrive. 
NO. 2777, VOL. IIT] 
—- 
NATURE 
75 
Early Mathematical Instruments in Oxford. 
Early Science in Oxford. By R. T. Gunther. Part 2 
Mathematics. Pp. ror. (London: Oxford Uni- 
versity Press, 1922.) 1os. 6d. net. 
HREE years ago a very interesting exhibition of 
early scientific instruments in Oxford was held 
at the Bodleian Library. A small printed list or 
catalogue of the exhibits was prepared at the time 
by Mr. Gunther, to whom all those interested in early 
scientific instruments are much indebted for bringing 
together the various early examples existing in the 
colleges of the University of Oxford, and making 
them available for inspection. It was intended that 
this small catalogue should form the basis of a more 
comprehensive work dealing with the history of science 
at Oxford, chiefly on the instrumental side. The 
first instalment (Chemistry) of this larger work was 
printed as a booklet in 1920 and afterwards published 
(see NaTuRE, March 3, 1921, p. 13). The second 
instalment, dealing with mathematics, has now been 
issued. 
The stated object of Mr, Gunther’s work is “ to 
draw attention to such material objects of value as 
still remain to us, with a view to their better preserva- 
tion, and to reviving the memory of the clever men 
who really helped science forward by the invention 
of practical methods, and by the cunning of their 
craftsmanship.” 
The first part of the booklet consists of “ Notes 
on Early Mathematicians.” One of the first mathe- 
maticians connected with Oxford was Daniel of 
Morley, who resided there in the year 1180, but went 
to the mathematical school at Toledo to complete his 
studies, and afterwards returned to this country as 
a teacher. The best known mathematician of this 
early period was the Yorkshireman, John of Holywood 
(Sacrobosco), who died in 1244. In the fourteenth 
century Richard of Wallingford, Thomas Bradwardine, 
John Maudith, Simon Bredon, John Ashenden, William 
Rede, and others, raised Oxford mathematics to a 
high level, and at that time “Oxford could boast 
more Mathematicians than any other country in 
Europe.” 
During the next century the study of mathematics 
was at a low ebb; in the middle of the century the 
only mathematical subjects required at Oxford for the 
master’s degree in the quadrivium were the first two 
books of Euclid and the astronomy of Ptolemy. 
Cuthbert Tonstall (1474-1559) and Robert Recorde 
(1510 ?-1558), the only two English mathematicians 
of note during the first half of the sixteenth century, 
commenced their studies at Oxford, but found that 
they could continue them better at Cambridge, and 
