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. 

 Recent 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- 

 'lium 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 Tornla, 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- 

 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- 



