Gnomonia ery thro stoma , Pers. 
589 
The Spermogonia. 
These are produced in enormous numbers on the under surface of the 
affected leaf-areas. Their external appearance has been already described. 
Occasionally two spermogonia coalesce to form a compound structure. The 
wall of the spermogonium consists of very closely compacted hyphae which 
form a kind of pseudoparenchyma. From the interior of the spermogonium, 
hyphae grow out towards the small circular orifice. These hyphae even at 
the base are much narrower than the vegetative hyphae, and they quickly 
taper to a point. The spermatia are formed by abstriction from the extremi¬ 
ties of these hyphae. A general view of a section through a spermogonium 
is seen in Fig. 3, a portion of which is shown on a more highly magnified 
scale in Fig. 4. The cells which give rise to spermatia are uninucleate, the 
single nuclei being larger and showing a more clearly defined network than 
the vegetative nuclei. The hyphae from which the spermatia originate, are 
often unbranched, though sometimes branching may occur as seen in Fig. 4. 
There is some evidence that more than one spermatium can be abstricted 
successively from the apical region of the spermogonial hyphae. In a mature 
spermogonium a few hyphae are seen to be distinguished from those giving 
rise to spermatia by growing further towards the orifice, and by their more 
deeply staining character. It is likely that these hyphae aid in the extrusion 
of the spermatia. 
The material was not favourable for observing details of the nuclear 
division which occurs prior to the abstriction of a spermatium. After this 
division, the daughter-nucleus which will become the nucleus of the sperma¬ 
tium rapidly becomes elongated. After separation of the spermatium from 
the hypha, the nucleus of the former is long and thread-like, and occupies 
a large part of the space within the wall. A relatively small amount of 
cytoplasm is present, most of which is found towards the lower end of the 
spermatium (Fig. 6). Under high magnifications the thread-like nucleus is 
seen to be not quite homogeneous, some portions staining more deeply than 
other (Fig. 6). 
The spermatia are straight at the time of formation, but most of them 
become curved to different degrees upon liberation from the spermogonium. 
Fig. 5 shows the diversity of form assumed by the spermatia. Sometimes 
the spermatium has the hooked shape of the spermatium of Polystigma 
rubruin (15), but more often the amount of curvature is only slight. The 
spermatia are from 8 /x—18 /x in length by about 0-5 /x broad. Frank gives 
the length of the spermatia as 14/X-16/X, but my experience is that the 
diversity in length is much greater than this. They are very slightly broader 
at one extremity than at the other, but the difference in this respect is much 
less marked than is the case with the spermatia of Polystigma rubruin. 
R r 2 
