188 MisceUaneoas. 



which tlont amoug the normal cells of the yeast, unite sometimes, 

 and appear also to be enveloped by a membrane. These granules 

 resemble in appt'arauce the masses into which we iind the cell- 

 contents divided in some cells ; and we tliink wo may affirm that 

 their number is greater in the preparations in which we observe 

 several cells which have folds or are ruptured, than in those which 

 do not present this condition. 



2. We have always obsei-ved in the vacuoles of the cells one or 

 two shining corpuscles, of a more or less deep yellow colour, and 

 endowed with an oscillatory movement. These corpuscles resemble 

 at the same time the other granules which, as already stated, float 

 freely in the exterior liquid and the protoplasmic granules which 

 occur in the cells outside the vacuoles. 



3. In yeast placed in water we have observed at the end of five 

 days cells folded in various fashions^ — some with the folds normal 

 to the lai'ger axis of the ellipse, others forming acute angles and in 

 a direction divergent from the centre to the periphery. Some cells 

 were constricted in a singular manner, forming a hood and re- 

 sembling in ap'pearance tliose blood-globules which were formerly 

 supposed to have an aperture. 



4. The action of heat causes the inflation of the cells even to 

 the rupture of some of them, the contents of which escape divided 

 into several parts, filling the field of the microscope with granules. 

 At the first moment of this action the volume of the vacuoles 

 increases by the union into a single ono of the two or more that 

 may be contained in the primitive cell. V/e have also observed 

 some cells in which the torn edges of the enveloping membrane 

 might be ver}- clearly seen. 



5. When the preparations of Saccharomyces cerevisice are treated 

 with concentrated sulphuric acid, we observe, leaving out of con- 

 sideration the rupture and natural destruction which is produced in 

 most of the cells, that the vacuoles swell very rapidly, the cells 

 acquire a homogeneous appearance and become diaphanous, also 

 becoming nearly spherical, and there is a production of gas. 



When this action is completed, at the end of twenty-four hours, 

 the cell consists of a portion of cell-contents contracted into a yellow, 

 homogeneous mass of almost spherical form, of an enveloping 

 membrane, which is more distinctly marked than before, and of an 

 annular space, which is observed between the latter and the yellowish 

 mass, and which has not the appearance of the vacuoles, nor that of 

 the homogeneous or granidated substances which fill the other cells. 



6. AVith phenol in fusion we see the cell-contents acquire some- 

 times a homogeneous appearance, sometimes that of a mass with a 

 few small granules. In all the cells we find a double contour, which 

 is due to the condensation of the phenol around the enveloping 

 membrane. The cells have a tendency to become spherical or 

 nearly so. 



7. Saccharomyces deprived of light presents the most remarkable 

 alterations. It is this that we have most carefully studied : and the 

 results obtained seem to us to merit most confidence. 



