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422

  THE NERVOUS

  SYSTEM

The Sensory Motor Functions of  the  Central  onvolutions of the Cerebral

Cortex F. W.

  M O T T .

  T he Jo ur n. of Physiology, vol. xv. Ja n.

1894.

T o those who have considered the anatomical bases on which the

physiological reactions of the cerebral cortex rest, nothing could have

been plainer than the fact that all parts of the cortical mass mu st be

both sensory and motor, if these terms are used with sufficient loose-

ness. W e ha ve clearly ma rked in th e cortex a locality in which im-

pulses pass from one nerve-cell to another, and in which the direction

of the impulse is changed, for incoming impulses arriving at the cortex

travel from the cord towards the brain, whereas those impulses on

which the moto r reactions dep end necessarily pass from th e brain

towards the cord. T his being the case, it was antic ipate d tha t injury

to the cerebral cortex would give rise to disturbances both of motion

and se nsation in the opposite half of the body. T he distu rban ce of

motion has been comparatively easy to d e te c t; but disturba nce of

sensation was both more difficult to determ ine a nd less co nsta nt.

Special localities for the dermal sen sations have been pr op os ed ; and

on the basis of exp eriment, Schafer and Horsley suggested tha t th e

gym s fornicatus was their cen tre ; but the re are good reasons for que s-

tioning this result.

So far as the work of M ott is conc erned , he inc lines to pla ce the

term inatio n of th e afferent fibres in very nea rly th e same loca tion

as tha t occupied by t he cell-bodies which give rise to th e efferent

fibres. Fr om th e na tur e of the c ase th e efferent fibres by m ean s of

the ir co llaterals may ha ve different term inatio ns, an d even in a given

locality term ina te in a diffuse m a n n e r; and, by conseque nce, very

limited lesions which m ay impair m otality do no t necessarily im pair

sensibili ty to the same degree. M ott s contr ibution to the subject is

briefly t h i s : M onkeys very carefully selected , on acc ou nt of their

sensibility, were operated upon in such a way that the connection of a

motor area was severed at some distance below the surface, the severed

portion being allowed to rem ain in place. Loss of m otion

  and

  loss of

sensation were found in the sam e regions, at the periphery ; and the

conclusion is drawn th at the so-called m oto r regions are nea rly coin-

cident with the localities in which the fibres for the dermal sensations

from these parts terminate in the cortex.

The Derivation of the Pineal Eye

Preliminary Ann ouncement. W M .

A.

  LACY.

  Anatom Anz., ix.  B. 5,  6.  1894.

Within the past seven years

  a

  large number

  of studies have

  been

made on the organ now

 known

  a s

 th e

  p ineal

  eye. Th is small structure

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PSYCHOLOGICAL  LITERATURE 423

is situated in the middle of the head just above the mid-brain, and in

some forms of amphibia and reptiles can be clearly seen from the out-

side. Through the work of de Graaf (1886) it came to be generally

accepted as an eye, constructed on the plan found among the inverte-

brates. Since that time its interpretation as a visual sense-organ, its

origin, its connections with the brain, and its functional condition, have

been widely discussed.

The observations of Lacy deal with its origin. In the Elasrao-

branch Fish  {Squahts acanthias he has observed in the neural plate,

behind the pair of depressions which later form the lateral eyes, two

other pairs of depressions similar in character. These two pairs be-

come associated with the mid-brain when the neural tube is formed.

The posterior pair disappears, but the anterior persists. The latter

forms parts of the roof of the m id-brain, and marks the locality at

which the epiphysis grows o u t In Squalus the pineal eye is not dis-

tinctly differentiated, but the enlarged end of the epiphysis may be

horaologized with it

The argument is therefore made as follows : The epiphysis origi-

nates from paired structures which in the first instance are comparable

with the optic depressions giving rise to the lateral eyes, and so the

final modification of the tip of the epiphysis into a visual sense-organ

would be in harmony with its early embryonic history. The paired

origin appears also to explain the fact that the pineal eye and epiphysis

appear in some forms to be distinct structures.

These observations are full of suggestion, and the next step, as the

author points out, is to determine whether in other animals the pineal

outgrowths have a similar embryonic history. H . H. D .

A N TH R O PO LO G I C A L.

The New Life: A Study of Regeneration A R T H U R

  H .

  DANIELLS,

Am.

  Jour, of Psychol., vi . 61 -10 3. Oct. 1893.

Mr. Daniells, with many other thoughtful theologians, believes that

theology has lapsed from its high functions, and has  become so

conventionalized and rigid that religion itself has often fallen into

disrepute and is losing its hold both upon the masses and the cultured

classes. But he believes that anthropology,  which is the pedagogi-

cal root and very lifespring of theology , has itself entered upon a new

stage of developm ent and is now ready

  to

  offer a few ripe insights

for the rehabilitation of theo logy , point by point. As an illustra-

tion of what is thus promised to theology and religion, Mr. Daniells

has made a very careful study of the phenom ena of puberty, viewed