MICOGRAPHIC STUDY OF SAFFRON DISEASE. 



23 



At the beginning- of the malady we perceive on the surface of 

 the bulb, if we separate slightly the fibres of the coat, little 

 orbicular brown spots of the size of a lentil. I believe that the 

 point of origin is generally that of the rootlets of the plant ; the 

 tissue is a little swollen at the circumference of the spots, so as to 

 form a sort of raised ring which is less strongly coloured. 

 Gradually these spots enlarge, and assume a darker tinge which 

 passes at last into black. They increase insensibly, and from 

 the confluence of many individuals lose their original orbicular 

 form. The malady, however, does not extend merely in width ; 

 the disease of the tissue penetrates into the substance of the bulb, 

 destroying the walls of the cells and the fecula which they con- 

 tain. At this period those deep excavations commence which 

 do not cease to be formed till the whole bulb is destroyed. The 

 cavity hollowed out in the substance of the bulb is not at first 

 visible, in consequence of the persistence of the coa t of the bulb, 

 which forms a sort of tympanum round the cavity, and does not 

 burst till a very late period. This happens at last from the 

 always increasing extension of the decay which constitutes this 

 formidable disease. When arrived at the last stage, all the base 

 and even the centre of the bulb is destroyed, and the whole 

 presents to the eye nothing more than a black dust formed by 

 the remains of the parenchymatous cells of the peridia of a 

 fungus of which I shall speak presently ; of the coats, or accord- 

 ing to M. Payen, of the tegumentary strata of the grains of 

 fecula ; and finally, which is not the least remarkable, of an 

 insect which lives in the centre of these debris, but this insect is 

 exactly the same as that which has been pointed out by M. Rayer 

 to M. Guerin Menneville as inhabiting the diseased potatoes, and 

 which the latter has named Tyroglyphus Feculce. 



Now if we make a vertical section passing through the axis of 

 the bulb, and examine under a lens the relation of the parts, we 

 perceive that beneath this pulverulent black stratum, composed 

 of the productions I have just enumerated, the parenchym is of a 

 reddish yellow tinge, and softened to the depth of from \ to J- of 

 a millimetre ; beyond this second layer the substance of the bulb 

 has at present remained sound. We want now to ascertain what 

 a microscopic examination of the parts will teach further. In 

 order to ascertain this, we must take with a razor an extremely 

 thin vertical slice, comprising at once, for the purpose of com- 

 parison, both the sound and diseased portions of the bulb ; if 

 the slice be then placed on a slip of glass in a drop of water, a 

 magnifying power of 50 diameters will show the whole at one 

 view. The same slice should then be transferred to the plate of 

 Schiek's Compressor, and after compression examined with a 

 power of 380 linear. The cells which are infested and form the 



