KING: CYTOLOGY OF ARAIOSPORA PULCHRA. 
217 
The Vegetative Plant. 
Although Araiospora has conspicuous constrictions at one or 
more places in its hyphae, it remains unicellular except where the 
reproductive organs are cut off. At the constrictions, the walls are 
thicker and show a slightly different chemical reaction. The cell 
wall consists largely of cellulose which responds differently in 
different parts of the plant. For example, when treated with 
chloriodide of zinc the large basal cell turns dark blue, the rhizoids 
blue, the hyphal filament violet, and the walls of the zoosporangia, 
of the oospores, and of the constrictions, rose to brick red. 
The cytoplasm consists of a fine meshwork in which are numer¬ 
ous, conspicuous nuclei (pi. 11, fig. 1-2). Figure 1 represents an 
almost median, basal cell. The protoplasm is confined chiefly to 
the region of the cell wall and surrounds a large central vacuole 
through which connecting cytoplasmic strands extend. In smaller 
filaments, the connecting strands are more abundant and thicker. 
The nuclei are often more irregular in form than those repre¬ 
sented in the drawing referred to above. In the younger parts of 
the plant they are more abundant and are usually elongated in the 
direction of the long axis of the filament (pi. 11, fig. 1). They 
have a sharp nuclear membrane lined within by deeply staining 
granules that are probably chromatin, a small nucleolus which takes 
the saffranin stain strongly, and an almost transparent nuclear 
substance. These vegetative nuclei are apparently poorer in chro¬ 
matin material for their nucleoli invariably show more distinctly 
than do those in either the zoosporangia or the sexual organs. 
The Asexual Organs of Reproduction. 
The zoo sporangium .— The cytoplasm of the zoosporangium of 
Araiospora is never homogeneously granular but consists of a 
distinct meshwork (pi. 11, fig. 3). In its early history, the meshes 
are irregular in size ; but as it matures they become finer and more 
uniform. During this early development the cytoplasmic strands 
contain granules as do those of the vegetative plant. In younger 
as well as in small mature zoosporangia, the cytoplasmic meshwork 
