34 MR. BERKELEY ON THE POTATO MURRAIN. 



place in the contents of the cells during the process of greening, 

 became in a few days highly diseased. 



7. Section of one of the dark patches on the stem which occur in the 



course of the disease. There is no trace of mucedinous filaments, 

 but the cells are filled with a dark grumous mass. 



8. Horizontal section of another patch exhibiting several mucedinous 



threads. 



9. Section of potato-leaf, showing the hyphasma of Botrytis infestans, 



Mont., creeping amongst the loose tissue of the underside, and 

 sending up fertile shoots through the stomate. The mould is still 

 young, one shoot not having at present formed any branches or 

 fruit. The tissue of the upper surface of the leaf is too compact to 

 allow the threads of the mould to traverse it. 



10. A portion of the cuticle of the lower surface, showing the threads 



of the Botrytis proceeding from the stomates. The mould, 

 with the exception of the plant at the left hand, is scarcely 

 more advanced than in the preceding figure. 



11. Portion of cuticle of the lower surface more highly magnified, 



showing three forms of stomates, from one of which proceeds a 

 young plant of Botrytis infestans. 



12. View of a horizontal slice of the cuticle of the lower surface of a 



leaf viewed from within, and showing the disposition of the sto- 

 mates in the reticulations formed by the loose tissue. 

 12.* Full-grown Botrytis infestans, from leaf; partly from a sketch 

 by Dr. Montague. 



13. Dwarf form from stem, sent from Bristol by C. E. Broome, Esq. 



14. Full-grown plant from tubers, partly from a sketch by Dr. 



Montague. 



15. Base of two filaments, 780 diam., from sketch by Dr. Montagne. 



This is not the normal structui-e, but merely a curious form as- 

 sumed by certain filaments accidentally detached from the hy- 

 phasma. 



16. Extremity of branch, with two swellings. 380 diam. 



1 7. Occasional appearance of spore. 380 diam. 



18. Spores with their contents, mag. ."^80 diam. 



19. Spores, 780 diam. This and the four preceding figures are from 



sketches kindly sent by Dr. Montague. 



20. Dactylium tenuissimum. Berk. 



21. Spores of ditto. 



22. Botrytis Arenarisc, Berk. 



23. Botrytis Vicia", Berk. 



24. Botrytis arborescens. Berk. 



25. Botrytis ganglioniformis. Berk. 



26. Botrytis parasitica, Pers. 



27. Artotrogus Hydnosporus, 3Iont. 



28. Thread of ditto, mag. 780 diam. 



29. Mature spore of ditto, 380 diam. This and the two foregoing 



figures are by Dr. Montagne. 



30. Tubercinia scabies, Berk. 



31. Cells from surface of ditto. 



32. Botrytis Bassiana, from a sketch by Dr. Montagne. 



