1904] JOHNSON—MONOCLEA 193 
with that of the chromosomes in the spermatogenous cells (jig. 8b). 
The fact that no other part of the spermatozoid retained the stain, 
and the constant agreement in number just mentioned, seems to leave 
no doubt that these threads in the spermatozoid are the greatly elon- 
gated chromosomes. The significance of this unique individuality 
of the chromosomes in the nearly ripe spermatozoid might be discoy- 
ered by a study of the process of fertilization and the behavior of these 
chromosomes in the fusion nucleus of the fertilized egg. This I was 
unable to accomplish because of a lack of material of the particular 
stage needed. 
THE ARCHEGONIUM. 
The portion of the thallus from which the archegonia develop is 
not as much differentiated from the vegetative part as is the male 
receptacle. The archegonia arise in acropetal succession, in groups 
of six to ten, on the upper surface of the thallus just back of the grow- 
ing point. At about the time of origin of the first archegonia of a 
group, for these differ considerably in age, the thallus begins to thicken 
just behind the growing point. A longitudinal section of this region 
at this time would look much like that of a young male receptacle 
(figs. 26, 27). Soon the upper anterior edge of this thickening grows 
forward to form a hood-like involucre above the archegonia (jig. 28). 
This hood-like roof above the archegonia keeps pace with the advance 
of the growing point below, and thus is formed the long, tubular 
involucre, which may become 1 5™™ or more in length, though seldom 
More than 3-4™™ in width (figs. 22, 29, 30, 31). Though widely 
open at first the involucre is finally closed anteriorly except for a very 
harrow slit, the edges of which fit together closely (figs. 22, 29, 31): 
After a growing point has given rise to a single series of archegonia 
and has done its part in ‘forming the lower side of the involucre its 
caeaes ceases. Then a new growing point appears on each side of 
the involucre at the anterior end (fig. 22). By the activity of these 
* new branch is formed on each side and the involucre is left behind 
at the juncture of these two branches. 
Lining the walls of the involucre on the inner side, among the arche- 
mes ora large numbers of glandular hairs, which are outgrowths 
a : Superficial cells. These are usually cut off by a transverse 
tom the parent cell (figs. 28, 33). These slime-secreting hairs 
