1886.] Himalayan Spruce-fir (Abies smithiana). 11 



EXPLANATION OF THE PLATES. 

 Plate I. 



1. Outline sketch, natural size, of three affected shoots (secidium) . 



2. Needle showing fully developed secidial fructification, about twice the 

 natural size : secidia in two rows on upper surface, excepting one at a on the lower 

 sxu'face. 



3. Young ^cidium emerging through a rent in the epidermis, with two sper- 

 magonia — slightly magnified. 



4. Showing mode in which pseudoperidium bursts : slightly magnified. 



5. Matting of mycelial filaments on surface of a parenchyma cell x 250. 

 Transverse section. 



6. The same x 250. Longitudinal section. 



7. -^cidiospore x 580. 



8. ^cidiospores with intercalary cells towards base of a series x 450. 



9. Fragments of hyphae in an air space x 450. 



10. Spermatia x 580. 



11. Haustorium in transverse section within a parenchyma cell x 250 (uredinal 

 affection). 



Plate II. 



12. Spermagonium : transverse section x 250. 



13. a. Portions of hyphee from a longitudinal section of needle affected with 

 uredinal fungus x 250. b. The same x 580. 



14. Convoluted mass of mycelium between parenchyma cells (uredo) x 430. 

 Transverse section. 



15. a. Basal cubical cells with nuclei (nucleus dividing in one which springs 

 directly from a hypha) x 580. h. Round basal cells in series x 580. c. Basal 

 cells with finger-like protrusions preparatory to formation of spores x 580. d. 

 Free uredo -spores x 580. 



16. Peridial cells x 340. 



Plate III (Photographs). 



17. General appearance of young shoots in an early stage of infection by the 

 secidial fungus, before the pustules have protruded through the epiderznis. 



18. The same when the fungas is fully developed. 



19. General appearance of a shoot attacked by the uredinal fungus : fully deve- 

 loped. 



20. Appearance of withered and dried up shoot after the death of the fangus. 

 (N. B. The four preceding figures about f natural size.) 



21. Transverse section of normal needle of Ahies smithiana. 



22. Transverse section of needle affected by gecidial fungus (the peridium with 

 the enclosed gecidiospores has accidentally become detached). 



23. Transverse section of needle affected by uredinal fungus showing four beds 

 of spores. 



24. Transverse section of needle affected by Chrysomyxa ahietis (?) intro- 

 duced for comparison with Figs. 22 and 23 as practically normal in all respects 

 excepting the protruding fructification. 



(N. B. The three preceding figures all magnified to the same extent.) 



25. Transverse section of needle affected with uredinal fungus more highly mag- 

 nified than Fig. 23 and illustrating several points referred to in the text ; more 

 especially the dislocation of the parenchyma cells and the comparatively undisturbed 

 condition of the tissues within the endodermal shenth. 



