24 



MIC0GRAPH1C STUDY OF SAFFRON DISEASE. 



base of the excavation will be found to have lost their ti ap- 

 parency; their once delicate tissue is thickened and granular; 

 their crystal-white has become dark-brown; and finally the fecula 

 has vanished, or only a few scattered injured grains remain ; 

 meanwhile their polyhedric form continues unaltered : this, how- 

 ever, is not the case with another stratum lying beneath the first, 

 and which separates it from the sound parenchym. This is 

 formed of cells perfectly hyaline it is true, but whose grains of 

 fecula have entirely disappeared. It is about the eighth or 

 tenth of a millimetre in thickness. The absence of the fecula is 

 not the only phenomenon which makes it remarkable. The 

 primitive dodecahedric cells, pressing against each other, form 

 prisms of five or six faces and of the length which I have 

 assigned to the whole stratum. These prisms thus disposed 

 exhibit a number of transverse lines which are formed by the 

 lines of junction of the faces of the cells. I cannot give a better 

 notion of it than by comparing it with the structure of the axis 

 of Chorda Filum, which I was the first to demonstrate, with this 

 difference however, that in the Alga the meshes of the net are, 

 or appear to be, quadrilateral, and besides less pressed against 

 each other. Finally, beyond the layer just mentioned, we find 

 the parenchym of the bulb in its normal condition, and the 

 hyaline cells, of which it is formed, filled with numerous perfectly 

 healthy grains of fecula. 



The details into which I have just entered respecting the 

 ravages caused by the Tacon present the closest analogy between 

 that disease and the potato murrain. Read in fact the descrip- 

 tions which have been given of it, which, from its frequent 

 occurrence, are unhappily too numerous; remark especially the 

 identity of the injury to the tissues, the more or less complete 

 evanescence of the fecula (an observation already made by 

 Fougeroux), the brown colour, and the granular thickening of 

 the cells of the parenchym — all, even to the presence of Tyro- 

 glyphus Feculse, confirms the analogy between the two diseases.* 

 And if we look to the causes, and make a parallel between the 

 conditions of development, we shall be the more convinced of 

 the justice of the comparison. There would indeed be some 

 essential difference between them, were we agreed on the indis- 

 pensability of the presence of Botrytis infestans on the leaves, &c. 

 of the potato before the attack of the tubercles ; but botanists 

 are still at variance on this much contested point. 



* I should however observe, that I find no trace of the filaments which 

 run between or within the cells of the parenchym, regarded by M. Payen as 

 mycelium, but as simple plaits in the cellul ar membrane by M. Decaisne. 

 [Both these positions are true, — sometimes in the same, sometimes in dif- 

 ferent cells. — 7r.] 



