218 Prof. A. B. Macallum. On the Nature of the [Mar. 3, 
precipitate which, in the normal cell giving the negative image, is to be found 
in the intercellular spaces and boundaries, that is, in the cement substance of 
Von Recklinghausen. Schweigger-Seidel maintained that the decomposition 
was brought about by chlorides forming silver chloride from the silver 
albumen precipitate in the intercellar material, the silver chloride so formed 
dissolving in the presence of chlorides, and thus diffusing into the cytoplasm, 
where, under the influence of light, it became the subchloride, and he proved 
this by taking preparations which had been treated with nitrate of silver, but 
not acted on by light, and placing them away from the light in a solution of 
sodium chloride. In these, when reduced by the light, the coloured silver 
salt or compound obtained chiefly in the cytoplasm. According to Hiiter* 
the positive image may arise through diffusion of the cement substance into 
the cytoplasm and the consequent intracellular precipitation of the silver 
compound. His,fin 1862, held that the silver compound in the cornea which 
reduces in light is not an albumin compound, but chloride of silver, for when 
the cornea was treated with mercuric nitrate, which dissolves chloride of 
silver, all the silver precipitate was dissolved, which would not have been the 
case had any of the compound been silver albuminate. In later observations,t 
however, he admits that the silver compounds may be an albuminate as well 
as a chloride, and that both reduce under the influence of light. A similar 
view was held by MHarpeck,§ Hartmann] Auerbach,! and Henle.** 
Schwalbe ff found that if the serous membrane to be examined be first 
washed with a 4-per-cent. sugar solution, treatment with silver nitrate will not 
bring out the silver lines usually obtained, and he concludes from this that the 
cement substance, such as Von Recklinghausen postulates, has nothing to do 
* “Zur Pathologie der Gelenkflachen und Gelenkkapseln, mit einem Kritischen 
Vorwort iiber die Versilberungsmethode,” ‘ Arch. fiir Path. Anat. und Physiol.,’ vol. 36, 
p. 25, 1866. 
+ “Ueber die Einwirkung des Salpetersauren Silberoxyds auf die Hornhaut,” 
‘Schweizer Zeitschr. f. Heilkunde,’ vol. 2, p. 1, 1862. 
t “Ueber das Epithel der Lymphgefadsswurzeln und iiber die Von Recklinghausen’schen 
Saftcanalchen,” ‘ Zeit. f. wiss. Zool.,’ vol. 13, p. 455, 1863. 
§ “Ueber die Bedeutung der nach Silberimpragnation auftretenden weissen liicken- und 
spaltahnlichen Figuren in der Cornea,” ‘ Arch. f. Anat.,’ 1864, p. 222. 
|| ‘Ueber die durch den Gebrauch der Hllensteinlisung Kiinstlich dargestellten 
Lymphgefassanhiinge, Saftcanilchen und epithelahnlichen Bildungen,” ‘ Arch. f. Anat.,’ 
1864, p. 235. 
4 “Untersuchungen iiber Blut- und Lymphgefisse,” ‘ Arch. f. path. Anat. und Phys.,’ 
vol. 33, p. 340, 1865. 
** “ Bericht tiber die Fortschritte der Anatomie im Jahre 1866,” ‘ Zeit. f. rat. Med.,’ 3e 
Reihe, vol. 30, p. 6. 
tt “ Untersuchungen iiber die Lymphbahnen des Auges und ihre Begrenzungen,” ‘ Arch. 
fiir Mikr. Anat., vol. 6, p. 1, 1869. 
