CHAPTER I.—HISTOLOGICAL CHARACTERISTICS. 5 
latter it is possible to give certain rules in individual cases; as a rule the sprouts may 
arise simultaneously at several spots in the mother-cell, or one after another from the 
same spot. If all the generations of sprouts continue united to one another, it is 
obvious that their combination simply forms an irregularly branched hypha, which is 
distinguished from ordinary segmented hyphae only by the constriction at the narrow 
„point of insertion of the sprout-cells. This is in fact the condition in which the cells 
remain as long as they are not disturbed; but eventually the full-grown sprouts 
separate easily from one another, and a slight movement leaves only isolated sprouts 
or small aggregates of them. 
The second exception is found in those simplest forms of the Chytridieae, in 
which the entire thallus consists of a single round cell which ultimately produces 
spores; the less simple species of this group are allied by their structure to the 
unicellular Filamentous Fungi described in sections XLVI-L. 
The Laboulbenieae may perhaps be reckoned as a third exception, but their 
character is still very imperfectly known (see Division II). 
The view given above of the structure and growth of the thallus of the 
Fungi has been already distinctly indicated in Ehrenberg’s Epistola de Mycetogenesi 
(Nov. Act. Acad. Nat. Cur. X); it is also clearly expressed in Vittadini’s Monogr. 
Lycoperdineorum (Mém. Acad. Turin. Ser. II, V, p. 146, 1841); and the views of 
later writers (Montagne, Esquisse organographique, &c. sur les champignons, Paris, 
1841, German edition, Prague, 1844, and Schleiden, Grundz. 3rd edition, II, p. 34) 
are in accordance with it. Schleiden, and Unger after him (Anat. u. Physiol. d. 
Pflanzen, p.149), call the weft of distinct hyphae felted tissue, ‘tela contexta.’ Thoroughly 
to establish and work out this view required fresh anatomical investigations, and to 
these Bonorden and Schacht have given the chief impulse and contributed the first 
more important materials. See Bonorden, Allgem. Mycologie, Stuttg. 1851, and 
Schacht, Die Pflanzenzelle, p. 134. ; 
On the clamp-connections see Hoffmann in Bot. Ztg. 1856, p.156; Tulasne, Carpol. 
I, 115; Bail in Hedwigia, I, 96, 98, &c.; Brefeld, Unters. über Schimmelpilze, III, 
especially p. 17; Eidam in Cohn’s Beitr. z. Biol. Bd. II, 229. 
The distinction of pseudo-parenchyma or apparent parenchyma was introduced 
by myself in the first edition of this work. The term may be retained as it has become 
familiar ; but it should be remembered, that it ought only to be used to indicate the 
appearance of the close short-celled tissue of the Fungus with reference to the ordinary 
conformation of the parenchyma of the higher plants. If the latter tissue is charac- 
terised not, as is most usual, by the form of its cells, but by their structure and by 
the functions indicated by their structure, then the pseudo-parenchyma is neither 
more nor less to be compared with it than any other aggregate of cells in the Fungus 
which serves for metabolism. 
The term Sprouting Fungus may be used as a general expression for the growth- 
form which it designates. As the Saccharomycete with this form of growth which has 
chiefly come under consideration is yeast, the term Yeast-fungus has usually been 
employed instead of Sprouting Fungus ; but this leads to confusion, and the word Yeast- 
fungus should not be used for the growth-form, but should be confined to the special 
cases to which it is suited. 
The Schizomycetes will be described in the third part of this work. 
Section II, The cells of the Fungi agree in all important points with the 
cells of other plants as regards structure, growth, and mode of division. 
The protoplasm, which in most cases fills uninterruptedly the interior of the 
young cell, encloses in the full-grown cell of the Fungi, as of other plants, one or 
