DIVISION I. GENERAL MORPHOLOGy. 



mengesetzer Pilzkorper) or simply a Fungus-body to distinguish it from that of 

 the simple Filamentous Fungus. Both are growth-forms (Wuchsformen) comparable 

 with those growth-forms in the higher plants which are known as the tree, shrub, 

 and herb. Many species appear only in the filamentous form, as succeeding 

 chapters will show ; others assume both forms according to their stage of develop- 

 ment and external conditions ; all have the filamentous form in their earliest stage. 

 It is obvious that intermediate forms will be found between these two chief ones. 



It has been assumed above that a hypha or a Filamentous Fungus is the product 

 of a single germ-cell, and this is often actually the case. It has been repeatedly 

 shown that even a compound Fungus-body may be composed of the ramifications 

 of a single filament proceeding from a single germ-cell. But this is not always 

 the case, or at least cannot always be proved, owing to the frequent coalescence 

 of similar hyphal branches with one another (Fig. i), which takes place in the 



FIG. i. Germinating gonidia of Nectria (Sffcarta) Solanf, 

 Retake ; a developing into an isolated hypha, in the rest the 

 hyphae have coalesced. Magn. 390 times. 



FIG. z. Clamp-connections of the my- 

 celium of Hypachttui ccntrifufus. Tut 

 Magn. 300 times. 



following manner : the lateral wall or the extremity of a branch or of a segment- 

 cell of the branch places itself on another branch or cell, and the membranes of 

 both disappear at the point of contact, so that the cavities and protoplasmic contents 

 of the two cells become united into one. Coalescence in this way may take place 

 between the branches of the same hypha, and also between such as are growing 

 together but were originally distinct, being the product of distinct germ-cells. The 

 forms which result from such coalescence are very various ; H-shaped cross links or 

 bridges, loops of various form and number, even network of many narrow meshes are 

 found. One curious form must be mentioned here, the damp-connections (Schnallen- 

 verbindungen), first observed by Hoffmann (Fig. 2). They occur only on hyphae with 

 transverse segmentation, and chiefly in the Basidiomycetes (many Agaricineae, species 

 of Polyporus, Typhula, Hypochnus, Cyathus, Hymenogaster, &c.). A clamp of this 

 kind when fully formed is usually a nearly semicircular protuberance like a short 

 branch which springs from one cell close to a transverse wall, and -is closely applied 

 to the lateral wall of the adjoining cell in such a way that the transverse wall cuts 

 the middle of the plane of contact at a right angle. Sometimes the protuberance 

 does not lie close on the lateral wall at all points, but forms an eye-hole. Brefeld 

 observed the origin of these formations in Coprinus, and found that the protuberance 

 extends itself from the one of the two adjoining cells to the other, and then 

 coalescence takes place, so that the two cells enter into open communication with 



