XXViii LIST OF ILLUSTRATIONS 



PAGE 



384. Atkinson's experimental intumescences on tomato. . . 509 



385. A. Lenticel proliferations (semi-asphyxiation tumors) on Ficus elastica 



(rubber tree). B. Vertical section of the same, enlarged 512 



386. 1, 2. Lenticel proliferations (semi-asphyxiation tumors) on Moms alba 



(white mulberry). 3, 4. Untreated parts of same branch 514 



387. Vertical section of one of proliferating lenticel tumors shown in figure 386 516 



388. A, B. Proliferated (semi-asphyxiated) and normal lenticel of Olea 



europecB (common olive) 517 



389. A, B. Proliferated (semi-asphyxiated) and normal lenticel in Begonia. . 518 



390. A, B, C. Tumors which formed accidentally on the sterile cut surfaces 



under the cork layer of a raw block of a potato tuber in a sealed tube 520 



391. Structure of the tumor at X on figure 390. 521 



392. Block of pared sterile raw potato with small tumors experimentally 



duplicating figure 390 522 



393. Tumors on top and bottom of a block of pared sterile raw potato growing 



in a sealed tube. Cork layer ruptured 523 



394 Blocks of raw potato showing development of callous tissue and small 



tumors in sealed tubes at room temperature 524 



394*. Well developed intumescences on silver spotted begonia due to paint- 

 ing with petrolatum in 1920 525 



395. Tumors on pared sterile surface of Early Rose potato tuber grown in a 



sealed tube on wet cotton 526 



396. Sterile cut surface of Early Rose potato tuber, showing a continuous 



series of tumors arising from the cambium and others not originating 



in the cambium 527 



397. Irish Cobbler potato showing tumors bursting through the normal skin of 



the tuber. Grown in a sealed tube on wet cotton 528 



398. Irish Cobbler from same series as figure 397. Tumors rupturing widely. 529 



399. General view of figures 397 and 398 showing method of treatment 530 



400. Intumescences (hyperplasias) developing under stomata on potato 



shoots in saturated air at high temperatures in bright light 532 



401. Like figure 400 but the basal intumescences fused and widely ruptured 



forming a collar 533 



402. Shoot of White McCormick potato grown in a sealed tube in the dark 



in saturated air at room temperatures base covered with intum- 

 escences, tip dying 534 



403. Sprouts shown in figure 399, enlarged X 5. Intumescences numerous. 535 



404. A, B. Same series as figure 403, but intumescences further ruptured. . . . 536 



405. Front and back view of a stunted swollen potato shoot exposed at 28 



to 35 C. and covered with intumescences. From a pared sterile 

 block in one of the sealed tubes : Effect of moist confined air, increased 

 CO 2 and decreased oxygen 537 



406. Pared sterile blocks of Early Ohio potato in sealed tubes in the dark at 



23-25 C., bearing shoots covered with intumescences ruptured and 

 unruptured. Tipt; of roots and shoots asphyxiated 538 



407. Hyperplasia under a stoma on a potato shoot (fig. 406). Medium 



magnification 539 



408. Stages of growth in a tumor (teratoma) which developed from the 



surface of a pared sterile block of potato in a sealed tube at room 

 temperature. Shoots covered with small hyperplasias 540 



