634 FUNGI 



invests itself with a cell-wall, and proceeds to germinate. This is 

 effected, both in the case of the zoospores and in that of the ordinary 

 spores, by putting out a germinating filament, which ultimately 

 develops into the new fungus plant. In a large number of fungi 

 no process of sexual reproduction is known. The various modes 

 which do occur will be described under the separate families. 



Some families of fungi are characterised by the remarkable pheno- 

 menon known as alternation of generations. Each species occurs in 

 two (or sometimes three) perfectly distinct forms, which bear no 

 resemblance to one another, and were long supposed to belong to 

 widely separated families. Each phase or 'generation' has its own 

 mode of reproduction, but does not reproduce its own special form, 

 but the other or one of the other forms ; and two or three generations 

 are thus required to complete the cycle. Each member of the cycle 

 is, generally speaking, parasitic on a totally different plant from the 

 ' host ' of the other forms. 



The classification of fungi is attended with very great difficulties, 

 owing to our still imperfect acquaintance with the mode of reproduc- 

 tion in several of the groups. The following are the more distinct 

 and remarkable types : ' 



The Myxomycetes, Myxogastres, or Mycetozoa, are a group of very 

 singular organisms, on the very confines of the animal and vege- 

 table kingdoms, doubtfully included among the fungi, and believed 

 1 >y many to have a closer affinity to the rhizopods. They appear, 

 indeed, at one period of their life-history to have an animal, at another 

 period a vegetable mode of existence. Several species are not un- 

 common on decayed wood, bark, heaps of decaying leaves, &c. The 

 plasmode ' of JJthaliitm septic-urn, known as ' flowers of tan,' forms 

 yellow flocculent masses in tan-pits. The development of other 

 species is represented in fig. 474. Commencing with the germina- 

 tion of the spores, each spore is a spherical cell (C) enclosed in a 

 delicate membranous wall ; and when it falls into water this wall 

 undergoes rupture (I)), and an amoeba-like body (E) escapes from 

 it, consisting of a little mass of protoplasm, with a round central 

 nucleus enclosing a nucleole and a contractile vesicle, and having 

 amoeba-like movements connected with the protrusion and withdrawal 

 of peculiar processes or pseudopodes. This soon elongates (F), and 

 becomes pointed atone end, whence a \o\\gflayellmn is put forth, the 

 lashing action of which gives motion to the body, which may now be 

 termed a swarm-spore. After a time the flagellum disappears and the 

 active movements of the spore cease ; but it now begins again to put 

 forth and to withdraw finger-like pseudopodes, by means of which it 

 creeps about like an Amoeba, and feeds like that rhizopod upon solid 

 particles which it engulfs within its soft protoplasm. These swarm- 

 cells may multiply by bipartition to an indefinite extent ; but after 

 a time ' conjugation ' takes place between two of these myxamoebce 

 (H), their substance undergoing a complete fusion into one body (I). 



1 [The classification of fungi here adopted is essentially that of De Bary in his 

 < '/iii/f/ai-atire Morjiholvf/i/ and Bioloijij of the Fungi, Myceiozoa, and Bacteria. 

 Owing to the very large recent additions to our knowledge of the structure of fungi, 

 it has been found necessary entirely to rearrange this portion of Dr. Carpenter's 

 work. ED.] 



