922 
IklE. J. LOCKHAET CLAEKE ON THE DEVELOPiMENT OF 
and variously-oblique fibres, continuous with roots of nerves, increase in a corresponding 
proportion and pursue a more definite course. But even at an advanced period of utero- 
gestation (at the fifth month, for instance, in the human foetus) the caput cornu is still 
very thickly crowded with nuclei, and presents an opaque and uniformly dark mass, like 
that of the foetal ox of 5 inches long, represented in fig. 14, Plate XLVI. By the end 
of the sixth month, however, it is much less opaque, and contains a much smaller pro- 
portion of nuclei, but a correspondingly large proportion of fibres running in the dhec- 
tions already indicated. Fig. 40, Plate XLVIII. represents, under a low power, a trans- 
verse section of one lateral half of the grey and white substances of the cord from the 
upper part of the lumbar enlargement of a human foetus of six months*. Here the 
caput cornu posterioris {I h) is at once distinguishable from the cervix^ not only by its 
bulbous expansion, but also by its much darker colour. The gelatinous substance, how- 
ever, and arciform fibres are not very strongly marked, but were readily detected under 
high magnifying-powers. In the larger and darker portion of the caput, the nuclei were 
imbedded in a fine granular network, and were most numerous at its sides, particularly 
its outer side. Amongst this network were the longitudinal and oblique fibres, to which 
in the adult cord the opacity of this part is chiefly due. The majority of the nuclei were 
round, but some were oval, and a few had an angular form. They were finely granular, 
were enclosed in distinct envelopes, and differed from each other in size. Then- average 
diameter was rather below that of the blood-globules of the same foetus. Scattered 
irregularly amongst these were a few others, which, in addition to the fine granules, 
contained each a larger, central and globular nucleolus. These latter nuclei were iden- 
tical in appearance with the nuclei of the larger nerve-cells. 
By referring to the same figure (40), it will be seen that each inner half of the cervix 
cornu [q) is occupied and rendered convex by a remarkable group of nucleated cells, 
which I formerly described very fully under the name of the posterior vesicular colmnnf. 
In this region of the cord (the upper part of the lumbar enlargement), not only are 
these columns larger than in any other region, but the cells which they contain are 
for the most part of the largest description, and similar in appearance to those of the 
anterior cornu : but their development is somewhat later. In the human foetus, at the 
sixth month, however, they are perfectly developed, and assume a variety of stellate 
forms, with processes that extend in all directions. They are closely invested by a thin 
* Through the kindness of Mr. Hatherlt, of Belgravia South, I was fortunate enough to obtain this 
fine male foetus within about an hour after death. The brain and spinal cord were immediately removed 
and hardened in the most gradual and careful manner by immersion, first, in an exceedingly weak solution 
of bichromate of potash, then in stronger solutions of the same salt, and finally in a solution of chromic 
acid. The preparations, of which a series of representations are given in Plate XLVIII., are the most 
beautiful that I have ever succeeded in obtaining from the human foetus. I must also acknowledge my 
obligations to Mr. E. Dunk, of Norfolk Street, Mr. Whitney, of Westminster, Mr. Painter, of West* 
minster, and Mr. Hunt, of South Belgravia, for their kindness in providing me with foetuses. 
t Probably a better term for this column would be the nucleus of the cervix cornu — nucleus cervicis 
cornu. 
