VIII Journal of Agricultural Research voi. xvn 



Bacterium abortus Infection of Bulls 



Page 



PivATE 22. Photograph of normal and diseased seminal vesicles of bull 98, show- 

 ing the marked increase in size and the gross pathological changes of one of 

 the organs 246 



Plate 23. A. — Photomicrograph of a section from a normal seminal vesicle of 

 bull. B. — Photomicrograph of section from seminal vesicle of bull 409, 

 showing inflammatory changes 246 



Plate 24. A. — Photomicrograph of section from seminal vesicle of bull 98, 

 showing tissue proliferation and exfoliation of epithelium lining acini. 

 B. — Photomicrograph of section from seminal vesicle of bull 98, showing 

 advanced pathological changes with cell degeneration and necrosis 246 



Investigations on the Mosaic Disease of the Irish Potato 



Plate A. Foliage of Irish potato, Green Mountain variety 274 



Plate B. Foliage of potato, Bliss Triumph variety 274 



Plate 25. Leaf of Irish potato, Green Mountain variety, infected with mosaic. 



Meditim stage of disease 274 



Plate 26. A. — Healthy scion grafted upon diseased stock. B. — An illustration 



of a method used for introducing aphids 274 



Plate 27. A. — Leaves from graft shown in B of this plate: At right, from 

 healthy parent of scion; at left, from mosaic stock; in center, from mosaic 

 • scion. B. — At left, healthy scion grafted to diseased stock. Green Moun- 

 tain variety; at right, two mosaic shoots of stock. C. — Leaves from cor- 

 responding parts of plants shown in Plate 29, B 274 



Plate 28. A. — 49IX, inoculated artificially with unfiltered juices from mosiac 

 plant February 22 to March 22, 1919. B. — 473y, inoculated in same way as 

 49IX, but with juices from healthy plant. 458y, also inoculated with juices 

 from healthy plant 274 



Plate 29. A. — Mosaic of potato transmitted by aphids. 142a, infected plant. 

 Green Mountain variety. B. — Two plants from the same tuber treated 

 alike, except that about 200 aphids were introduced upon one when it was 

 2 inches high 274 



Plate 30. A. — Inoculated by means of artificial transfers of aphids from dis- 

 eased plants. Green Mountain variety. B. — Plants inoculated in same 

 way as those in A of this plate, but with aphids taken from healthy plants. . 274 



