66 British Uvredinee and Ustilaginee. 
-Subjoined is a summary of his observations. The 
mycelium pervades all parts of the affected plant, excepting 
the roots. It consists of intercellular, branched, sparsely 
septated, hyaline hyphz, having a diameter of from 2 to 
3u. It is most abundantly distributed in the cortical 
tissues, and sends botryform haustoria (Plate VI. Fig. 1) 
into the adjacent cells. At certain places it gives off 
smaller, more richly septate branches, unprovided with 
haustoria, which are destined to form the spore-beds. This 
is accomplished in the following manner :—A number of 
straight and rather larger branches are given off, which 
soon become curved and interwoven in various ways, gene- 
rally more or less spirally, so as to form an entangled knot. 
The spore-bed which this entanglement forms develops 
spores from within outwards ; each spore-ball contains from 
fifty to a hundred spores, The spores measure from 55 
to 75u in diameter, and consist of an endospore, containing 
granular protoplasm, and an exospore. No gelatinization 
of the spore-forming hyphe, such as takes place in the 
spore-formation of Sorosporium saponari@, was observed. 
Tilletia.—The spore-formation in this genus was first 
indicated by Tulasne,* afterwards by Kiihn,t who gave 
a figure of the process; but it is to Von Waldheimt 
that we are indebted for the most detailed account. He 
thus describes the process: The vegetative mycelium of 
Tilletia tritict is nearly 24 in diameter. The swelling 
and gelatinization of the spore-forming hyphze is not so 
marked as in Ustilago, so that the lumen of the hyphe 
is never so contracted. Spore-formation begins by the 
hyphe giving off pyriform buds, 1°35 across (Plate VI, 
Fig. 4), in succession, from their sides ; these outgrowths in- 
* Tulasne, ‘17 Mémoire sur les Ustilaginées comparées aux Uredinées,” 
Pp: 27, e¢ seq. 
+ Kiihn, ‘‘ Krank. der Kulturgewachse,” p. 56, t. iv. fig. 5. 
t F. von Waldheim, Joc. cet. 
