THE MICROSCOPE IN HISTOLOGY AND BOTANY. 135 



vegetable tissue. They also differ from ordinary vegeta- 

 bles by the total absence of chlorophyll or its red modifi- 

 cation. A large number of this strange class are micro- 

 scopic, and require high powers for their observation. 

 Eecent investigations show that individual fungi are de- 

 veloped in very dissimilar modes, and are subject to a 

 great variety of form, rendering it probable that those 

 which seem most simple are but imperfectly developed 

 forms. Amoeboid motions also in the cell-substance of 

 certain kinds of fungi, and the projection of threads of 

 bioplasm, show a great resemblance to some of the lower 

 forms of animal life, as the Rhizopods. 



All fungi exhibit two well-defined structures, a myce- 

 liuin or vegetative structure, which is a mass of delicate 

 filaments or elongated cells; and a, fruit or reproductive 

 structure, which varies in different tribes. In Tonda, one 

 or more globular cells are produced at the ends of fila- 

 ments composed of elongated cells ; these globules drop 

 off and become new mycelia. The " yeast plant," or Torula 

 cerevisia (Plate IX, Fig. 107), receives its name from its 

 habitat. Fermentation depends upon its presence, as pu- 

 trefaction does upon the minute analogous bodies called 

 Bacteria and Vibriones. Bacteria are minute, moving, 

 rod-like bodies, sometimes jointed ; and vibriones are 

 moniliform filaments, having a vibratile or wriggling: mo- 



O SO O 



tion across the field of view in the microscope. The re- 

 searches of Madame Luders render it probable that the 

 germs of fungi develop themselves into these bodies when 

 sown in water containing animal matter, and into yeast 

 in a saccharine solution. The universal diffusion of spor- 

 ules of fungi in the atmosphere readily accounts for their 

 appearance in such fluids, and Pasteur's experiments are 

 quite conclusive. 



The minute molecules called microzymes, present in va- 

 rious products of disease, as the vaccine vesicle, fluid of 

 glanders, etc. ; the minute corpuscles which cause the dis- 



