IRON COMPOUNDS IN ANIMAL AND VEGETABLE CELLS. 231 
as deeply stained, and in these one finds the existence of rod- 
lets indicated, such as those to which I have referred above; 
but these (les stries transversales de la queue) are more ap- 
parent in the penetrating than in the free spermatozoid. I 
observed only faint traces of such structures in the spermato- 
zoid in the interior of the ovum, the rodlets apparently com- 
mencing to disappear immediately impregnation is accomplished. 
The chromatin of the nucleus of the ovum gives a deep 
reaction for iron in whatever stage the nucleus may be found 
(figs. 29 and 30). The chromatin also of the “ polar globules” 
contains iron, and I made efforts to determine the ultimate 
fate of this, but these were unsuccessful. It would appear, 
however, as if the chromatin of the extruded elements were 
dissolved eventually in the cytoplasm, for it is impossible to 
find any traces of it after a time. 
Chironomus.—Balbiani,! who was the first to call the 
attention of cytologists to the structure of the nuclear elements 
in the “salivary” glands of the larva of Chironomus, de- 
scribed the nuclear filament as made up of a series of dim discs 
or bands, each placed transversely, and separated from its 
neighbour on either side by a band of clear substance, the 
filament possessing, however, at certain points an annular 
swelling, and terminating at its ends either in the polymor- 
phous nucleolus or by an attachment to the nuclear membrane. 
Leydig,” the next observer, found each dim stria to be made 
up of a series of elements whose separation from each other 
gives a composite character to the stria. The fine lines sepa- 
rating the elements are, according to his observation, con- 
tinued from one dim disc, through the light disc on either side 
of it, to the adjacent dim disc. In this way a series of exceed- 
ingly delicate longitudinal lines, in addition to the coarse trans- 
verse ones described by Balbiani, make their appearance. 
Leydig also believes that the substance forming the dim band 
1 «* Sur la structure du noyau des cellules salivaires chez les larves de Chiro- 
nomus,”’ ‘ Zool. Anzeiger,’ 1881, pp. 637 and 662, 
2 Untersuchungen zur Anatomie und Histologie der Thiere,’ Bonn, 1883, 
p. 90. 
