REPORT OF THE SOCIETY 119 



under the microscope, it is found that the multicellular ends of the glandular 

 hairs are all dark brown. Furthermore, these structures are considerably more 

 numerous on diseased than on healthy plants, on which last the trichomes are 

 green in colour. 



One observation worthy of note is that all the tomato plants here at 

 Macdonald College infested with stripe also had mosaic. In man}' cases the 

 mosaic symptoms were not clearly apparent at first; but the characteristic 

 symptoms always developed later, the light green and dark green patches 

 being distinctly clear cut. 



Some Internal Symptoms. 



(i) The stem. — Cross sections of diseases stems show that usually th^ 

 brown lesions are onlj- superficial, but in some, the necrosis extends well int° 

 the cortex, and in others again, the pith is invaded as weP. The vascular ele" 

 ments do not show any definite symptoms of necrosis. Longitudinal sections 

 taken at the junction of the petiole with the stem show that the necrotic tissue 

 leads from the one into the other, either by the cortex, or by the pith or bj^ both. 

 Small brown patches are also found in the pith and cortex. 



(2) The petiole. — Internal sj'^mptoms are similar to those of the stem; 

 but the extent of the internal browning ranges from lesions including the epi- 

 dermis and a few layers of cells of the cortical tissue to cases where the whole 

 petiole is necrotic — all the tissues being affected. The course of the brown 

 area can be traced from the cortex into the pith, the vascular elements being 

 unaffected in the majority of cases. 



(5) The leaves. — All the tissues of the leaf except the vascular bundles 

 become necrotic. There is a shrivelling and drying up of the lamina in affected 

 areas and here the walls are quite brown. The cells in such areas and those 

 closely adjoining appear to be completely collapsed and desiccated. Such tissue 

 stains very deeply with Gentian Violet and Carbol Fuchsin. It cannot be 

 definitely stated that bacteria are or are not present; for, on the borders of 

 some lesions short rods which have taken the stain deeper than the surrounding 

 material, are observed in small numbers. If they are bacteria, they are far 

 fewer in number than is commonly the case in plants attacked by bacteria and 

 they may be secondary in the lesions. 



Enlarged nuclei are often found in cells adjoining necrotic lesions. Affected 

 leaves are found to possess an abnormal number of cells containing shining 

 crystalline deposits which will not stain. 



(4) The fruit.— The spots on the fruit are usually superficial and include 

 onlj^ a few layers of cells. Occasionally brown streaks and patches of tissue 

 are noticed interspersed here and there within the fruit. 



(5) The roots. — The roots from twelve severely diseased plants were 

 examined by cutting longitudinally and transversely but no indications of 

 the presence of bacteria were observed in any case. 



