MODERN RESEARCHES INTO THE NATURE OF YEAST, 149 
septa or constrictions, the growth of the cells then entirely 
ceasing. In this condition the buds are also the result of 
outgrowths of the mother-cell, but only a small portion of the 
latter takes part in their production. The bud has only a 
limited power of elongation, and becomes separated from the 
mother-cell not by a septum but by constriction, although a 
line of demarcation between the two modes cannot be 
accurately laid down. 
The researches of Seynes,' and Reess,? show that under 
certain circumstances endogenous cells or ascospores are pro- 
duced by Mycoderma and Saccharomyces. Their formation 
is induced by a very poor nutrient fluid, or by placing the 
organisms on a solid substratum, such as slices of potato or 
carrot. Cienkowski has confirmed the result in both cases. 
Mycoderma vini placed on boiled pieces of carrot, grew 
luxuriantly for some days. The ascospores first make their 
appearance after about a week, if the organism is not 
entirely overgrown by Mucor, Oidium lactis, &c. They 
occur in small isolated cells as well as in those still in 
connection with the filaments (fig. 6 a, 6); but were never 
HiGanO- 
observed in those that had attained any great length. Their 
minute size (0°004 mm. in diameter) rendered it difficult to 
observe the manner in which they were formed ; apparently 
they are produced, not by free cell-formation, but by sub- 
division of the entire contents of the cell. In the cells in 
which the ascospores are about to be formed the contents of 
the cell become denser, and then split up into four plates, 
or into as many wedge-shaped portions (fig. 4 c,d, e). The 
1 « Sur le Mycoderma vini,” ‘Ann. des Sci. Nat.,’ 5th series, 1869, vol. x. 
* «Botanische Untersuchungen,’ p. 10. 
