182 
the spore-bearing layer, which occupies almost all the space not taken up by the ostiole- 
The cells lining the cavity arch inward, and elongate to form a stalk, from the tip of je 
the pycnospore is abstricted. 
The pycnospores are ellipsoid and colourless, and do not turn brown at any time ; 
they are 18-20 » x 5-6 y in dimensions. 
Physalospora Perseae, nov. sp. 
Peritheciis sparsis v. gregarus, tectis, ostiolo papillato erampente, atris, ellipsoideis 
v. subglobosis, 130-190 u x 100-120 Mm: ascis clavatis, paraphysatis, 80-100 u x 18-23 u, 
octosporis : paraphysibus filiformibus, ndmerosis, hyalinis : sporidiis distichis, continuis, — 
hyalinis, ellipsoideis v. subfusiformis utrinque obtusis, 20-21 » X 8-10 u. Pyenidiis sab- 
globosis v. ellipsoides, 120-130 » x 70-187 mu; sporulis hyalinis Sihnavidest 18-20 u X 5-6 u. 
Hab. in foliis Perseae americanae, Louis fas uses Transvaal, 25.4.21, leg. 
J. H. Cronwright. 
When the spores have been discharged from the pycnidia or perithecia, one fnoquently 
finds the cavity occupied by another fungus, which is probably a saprophyte or secondary 
parasite. This organism produces spherical pycnidia about 90 u in diameter, and filled 
with: small, narrow, ellipsoid, fuliginous, two-celled spores. 
The Fungus in Culture. 
The fungus was isolated a number of times from diseased twigs by plating (1) ascospores 
and (2) pycnidia in agar, and (3) from the myceliam present in small pieces of diseased 
wood, In each case the same fungus was obtained, and the cultural characters were 
identical. It grows readily on most of the culture media in common use, but as the fruiting 
bodies develop slowly it was found advisable to use conical flasks rather than petri dishes 
for culture work, as the latter dried out too rapidly. 
Cultures on prune agar, oatmeal agar, and maize-meal agar were kept in the green- 
house in a bright diffused light. The mycelium is at first cottony, but after a few days 
the submerged hyphae are green or blue-green for some time, after which the growth is 
dark or nearly black. The outer ends of the aerial hyphae maintain their original cottony 
appearance and become greyish in colour. Cultures in active growth often show distinct 
zoning. Thus far the fungus Physalospora Perseae closely resembles in its cultural characters 
Ph. Cydoniae, which is parasitic in apple twigs,* but the formation of pycnidia is very 
different from that observed in cultures of the latter fungus. 
The submerged hyphae, as seen by transmitted light, are olive-green or brownish in 
colour, and are about 3 thick; the aerial hyphae are more slender and hyaline. After 
three or four weeks on oatmeal agar small bodies consisting of tangled masses of hyphae 
appear on the surface of the culture ; these increase in size until they form tussocks, 
3-6 mm. in diameter and about 3 mm. in height; these are dark-coloured bodies, but 
with a thin covering of the cottony aerial mycelium. After about six weeks the top of 
those bodies becomes covered with hard, black pustules, from which seven to eight weeks 
old cultures masses of conidia ooze out. 
A cross-section through one of the sclerotial bodies first observed in a three weeks old 
culture shows that it consists of tangled masses of hyphae similar in form to the submerged 
hyphae of the ordinary mycelium. Later there is a differentiation with a sterile base, 
consisting of interlaced dark-coloured hyphae, brown or olive-green, by transmitted light, 
and an upper portion of more closely woven, lighter-coloured hyphae in which a number 
of cavities are developed. These are irregularly arranged in one or more layers, ellipsoid 
or flask-shaped—usually papillate, 250-320 u x 130-2004. The inside of the cavity 
is lined with a layer of compressed hyaline hyphae, which eventaall y arch inwards and form ~ 
the Ver sedes The tip of the conidiophore swells up and the mature conidium is cat off. _ 
* Hesler, L. R. : Black Rot, Lea’ Spot, and Canker of Pomaceous Pruite, Cornell, Univ. Agric, — : 
Exp. Sta. Bull. 379. Aug. 1916. mee 
