559 



In conclusion, we heartily recommend this little publication to the 

 notice of our readers, as one of the prettiest botanical presents that 

 could be made to their juvenile acquaintance. 



K. 



Microscopical Society^ May 13^^, 1846. 



J. S. Bowerbank, Esq., President, in the chair. 



This evening a paper by E. J. Quekett, Esq., entitled " Some Ob- 

 servations on the microscopic appearances in diseased Potatoes of the 

 present season " was read. After some preliminary observations, Mr. 

 Quekett went on to state that if a section be made of a potato in which 

 the disease is only just commencing, it will be observed that a large 

 quantity of fluid follows the incision, and that many minute points, of 

 a brown colour, of various sizes, may be detected in the cut surface. 

 As the disease advances, these spots become larger, those on the sur- 

 face being of a brownish black, and exhibiting evident marks of the 

 commencement of decomposition in them. If very thin sections of 

 the interior diseased portions be submitted to the microscope, it will 

 be seen that certain cells, beside containing grains of starch, have for 

 the most part their walls lined with a brown, granular matter, the par- 

 ticles being very minute. In a section from the exterior, where the 

 marks of the disease have become very manifest, all the cells are found 

 to be of this brown colour, and masses of irregular, grumous matters 

 occupy their interior. Upon close examination tubes may be disco- 

 vered between the cells, containing minute granules, which tubes 

 branch according to the interspaces of the cells, and it often occurs 

 that the interspaces appear to be filled with granules alone. These 

 appearances are referred by Mr. Quekett to the presence of minute 

 fungi, whose growth is exceedingly rapid, and which appear under 

 the forms of particles, sporidia and filaments. The particles, which 

 are not ^Tj^iy-^ of an inch in diameter, appear to compose the greater 

 portion of the mass of diseased structure : they require a power of at 

 least 300 linear to separate them. The sporidia are of various sizes, 

 the larger a little curved, and containing some nuclei or cytoblasts 

 within, and probably are species of the genus Fusarium. The fila- 

 ments are jointed and branched, and contain granular matter. A mi- 

 nute fungus, having filaments, bearing globular heads containing 

 sporules, apparently belonging to some species of Botrytis, is also 

 frequently seen on the exterior. The author then proceeded to state 



