IRON COMPOUNDS IN ANIMAL AND VEGETABLE CELLS. 229 
some important variations were found in the disposition of 
the iron-holding substance, and it was further determined 
that in non-nucleated organisms the exceptional distribution 
of the chromophilous substance is co-extensive with that of 
the assimilated iron compounds observed. Such facts are 
worthy of an extended description, and I now propose to 
detail these and the more important observations allied to 
them. 
Ascaris.—In the species A. mystax the spermatozoids 
and ova, both before and after fertilisation, manifest special 
features in the distribution of the iron-containing substance. 
When they are hardened in alcohol, the spermatozoids are 
comparatively easily affected by the ammonium hydrogen 
sulphide, the reagent, mixed with glycerine, giving in a couple 
of days, under the usual conditions, a reaction for iron, which 
usually is confined to the “nucleus,” a dense homogeneous 
body (fig. 81) ; but in several instances the ‘“‘membrane” also 
contained iron. The reaction in the latter varied in intensity, 
and when most marked it revealed a structure in the “ menm- 
brane ” like that represented in fig. 82. The iron compound 
observed in such a case obtained only in the rodlets constitut- 
ing the “membrane.” What the occurrence of assimilated 
iron in this situation signifies I am unable to say, except that 
it possibly represents an abnormal phase of a condition normal 
to the spermatozoid after it has penetrated the ovum. When 
the spermatozoid begins to penetrate the latter, its membrane 
frequently manifests a weak reaction for iron (fig. 29), while 
its cytoplasm does not give any evidence of the presence of 
that element; but in the changes it undergoes after reaching 
the interior, the “ nucleus”? becomes in part dissolved, and 
the chromatin, as shown by the iron reaction, diffuses into 
the cytoplasm and into the membrane, from which some of it 
passes into the cytoplasm of the ovum immediately adjacent to 
the spermatozoid. The membrane in this way becomes the 
most prominent part of the spermatozoid. As the transforma- 
tion proceeds, the membrane also dissolves, and the iron which 
it contains appears to pass back again into the cytoplasm of 
