ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
325 
As it was evacuating elliptical corpuscles he imagined that these were the 
eggs of a nematode, and that there was a nematode within. However, 
on dissection, not a parasite was found. Nor were the corpuscles coccidia. 
Maceration of the walls of the intestine showed that the bodies were the 
nuclei of mucus-producing cells ; the cells become destroyed in conse- 
quence of their activity, and the nuclei escape in consequence of being 
protected by an envelope. 
Structure of the Spinal Cord in Human Embryos.* — Prof. A. von 
Kolliker finds in the spinal cord of human embryos a corroboration of his 
conclusions in regard to that of other mammals. The fibres of the sen- 
sory roots divide as they enter the cord into an ascending and a descend- 
ing branch ; the longitudinal fibres of the strands in the cord give off 
collateral fibres which ramify in the grey matter and end in tufts ; the 
anterior commissure is clearly seen in the neck and loin regions as a 
crossing of fibres, most of which arise from the axial processes of cells 
in all parts of the grey matter ; these do not pass, as regards the com- 
missure, into root-fibres, but into longitudinal elements of the anterior 
and an ter o- lateral strands. Sections prepared according to Golgi’s 
method of staining, differentiate the elements as effectively as do those 
of Flechsig, and Weigert’s method is also satisfactory. 
Optical Characters of Medullated and Non*medullated Nerve- 
Fibres.j — Herr H. Ambronn demonstrated, in 1888, that the optical 
peculiarities of cork and some other vegetable tissues were due to 
crystalline particles of a wax-like substance. As medullated nerve-fibres 
differ optically from muscle, sinew, &c., as cork differs from most 
vegetable tissues, it seemed likely that the refraction peculiarities of 
medullated fibres were also due, as Klebs and Kiihne suggested, to 
crystalline particles. By careful experiments, Ambronn convinced him- 
self that the body to which the nerve owes its optical peculiarities is 
lecithin. This conclusion Gad and Heymans have corroborated in 
another way. According to Ambronn, the substance, both of medullated 
and non-medullated fibres (apart from Schwann’s sheath), shows, in the 
absence of myelin or lecithin, the normal positive double refraction. If 
the lecithin be present in the form of very small crystals, with their 
optical axes radially and uniformly arranged, the positive double refrac- 
tion of the matrix will be disguised ; the opposite character will appear 
to a degree varying with the quantity of lecithin. But the use of ether 
will always bring out the positive character of the matrix-substance, and 
the optical change affords an index to the quantity of lecithin present. 
Histology of Spermatozoa. :f — Mr. G. Dubern, working with a quarter 
and an eighth, and very intense sources of light, has discovered that the 
head of the human spermatozoon is composed of a number of closely set 
minute spheres, and that the tail is composed of thirty-five to forty small 
spheres, “ very much like the beads of a single-row necklace.” The 
wide generalizations that these and other observations have induced the 
author to formulate will be found in the author’s paper. 
* SB. Physik.-med. Gesell. Wurzburg, 1890, pp. 126-7. 
t Verh. K. Sachs. Gesell. Wiss., 1890, pp. 419-29. 
X Indian Med. Rev., ii. (1891) pp. 30-6. 
