234 Dr. A. de Bary on the Mycetozoa. 



minal cell and of an additional member or joint to the series or 

 row, which may be called the "segment-cell" ("Gliederzelle"). 

 In the latter, fission either does not recur at all, or speedily 

 comes to an end. On the other hand, the " segment-cells " shoot 

 forth lateral saccular buds which, by the subsequent develop- 

 ment of septa, constitute twigs or branches upon the primitive 

 cell. All the septa in a branch are disposed one above the other 

 in parallel order. 



The thallus of the simple varieties of Fungi (the filiform 

 Fungi or " moulds ") is composed of hyphse disconnected, or at 

 most only approximated, in the act of growing. Fungi of a 

 higher grade of development, which attain a spongy consistence, 

 are formed of the same sort of fibres intertwined. The growth 

 of such Fungi in breadth and thickness, apart from the simple 

 expansion of the existing cells, is dependent on the formation of 

 new histological elements, and proceeds from the development of 

 offshoots to the contiguous hypha? which are interposed between 

 the original portions of tissue, or are overlaid upon the surface 

 of the organism. 



Indeed in the case of the seemingly more complex tissues of 

 many Fungi for example, of the external layer of many Agarici 

 (Russula), the bodies of many Pyrenomycetes, the skin of the 

 warty species of Lycoperdon, &c. there is a near resemblance to 

 the parenchyma of higher organisms in the appearance of juxta- 

 posed globular or polyhedral cells, when a thin section is sub- 

 mitted to examination. In fact, however, the study of the de- 

 velopment of such tissues proves that they likewise originate in 

 the interlacing of hyphaB, and that their exceptional appearance is 

 due to a subsequent expansion and displacement of the segments 

 of the filiform fibres. 



The construction and growth of Fungi therefore characterize 

 them from all other Cryptogam ia, such as the Fucacese and 

 Florideas, which exhibit the cellular structure and cell-develop- 

 ment of higher plants. It is only in the formation of the repro- 

 ductive organs that cells and cell- corpuscles are concerned in 

 any of the Fungi. Nevertheless, the whole history of the 

 organisms leaves no doubt of the vegetable nature of the true 

 Fungi. 



The systematic position of the entire class, as determined by 

 affinity of structure, is in connexion with Peronospora, Syzygites, 

 in the family Siphonsea, of which the best-known example is 

 furnished by the genus Vaucheria. Indeed, the Fungi are so 

 intimately allied to this family through the group of Saprolegnia3 

 (e. g. Saprolegniaferax, Achlya prolifera), that the latter might 

 with almost equal reason be referred to the Fungi. Like these, 

 the SaprolegniaB grow on diseased and dead organisms, and are 



