882 



SCIENCE. 



[N. S. Vol. XLIII. No. 1121 



and now in blossom. To get such prompt, 

 disastrous results, the inoculation must be 

 fairly early in the life of the plant and near 

 the growing point. 



Secondary infections due to other organ- 

 isms are also as common and as disastrous in 

 crown gall as in cancer in man. Just now 

 in the hothouses we have striking examples 

 of it on the Paris daisy and I will show 

 you a few slides. (Slides.) These second- 

 ary infections may be either fungous or 

 bacterial. 



Third, let me show you some examples of 

 infiltration, taken from sunflower heads in- 

 oculated last year. The first three slides 

 show hard greenish gray vascular tumors 

 which have developed from a few needle 

 pricks made into the extremely vascular 

 thin layer which bears the seeds. The one 

 shown in vertical section is from the middle 

 of the flower disk and it has grown down- 

 ward in the white pith for a distance of 4 

 inches. It lies in the pith but has not de- 

 veloped out of pith. The fourth slide from 

 another tumor shows cancerous cells and 

 vessels of the supporting stroma pushing 

 out into the sound tissues much as roots do 

 into a fertile soil. The fifth slide is from 

 the cortical part of a teratoma on Pelar- 

 gonium. Here the small-celled blastomous 

 tissue has crowded in between coarse cells 

 of the cortex. 



Next to be considered are examples of 

 atypical blastomous tissue taken from dif- 

 ferent parts of the same tumor (a young 

 deep inoculation into the stem of a Paris 

 daisy). In the first slide, at the left, is a 

 part of the supporting stroma (cortex 

 cells) ; the right side shows round cells of 

 the same type that have become cancerous, 

 i. e., much smaller, more embryonic, rapidly 

 proliferating, large-nucleate and deep- 

 staining cells which have lost their polarity. 

 The second slide shows spindle-shaped blas- 

 tomous cells from the outer part of the 



same tumor. This tumor is the ordinary 

 rough gaU of the daisy stem, which is a sar- 

 coma as near as the plant can make one, 

 that is, a sarcoma minus the intercellular 

 fibrils which are wanting in plants. 



Now let us consider how plastic the liv- 

 ing tissues can be when they are brought 

 under a cancer stimulus. I show you photo- 

 micrographs of tumors (atypical hyper- 

 plasias) produced by inoculating the crown- 

 gall organism into the extreme outer bark 

 (living cortex) of young stems of Paris 

 daisy, the inoculated cells being ordinary 

 cortex cells. These tumor cells which con- 

 ceal the bacteria (there are none in the in- 

 tercellular spaces) have become more em- 

 bryonic than the tissue out of which they 

 have grown. This is shown by their size 

 (%o that of the cells from which they have 

 developed), their large nuclei and their 

 avidity for stains, as well as by the pecul- 

 iar way in which they fix the stains. It is 

 also shown by the fact that they can pro- 

 duce vessels in their midst (trachei) 

 whereas the uninjured cortex never pro- 

 duces vessels. The embryonic tissues of the 

 plant, however, have this vessel-producing 

 power. In a word, these tumor cells have 

 become more embryonic than the tissue out 

 of which they have developed and have lost 

 their polarity, and this is exactly what 

 occurs in cancer in man, as I shall show 

 you. I have produced these superficial fine- 

 celled hyperplasias out of coarse-celled cor- 

 tex, not once, but a number of times, and in 

 several different kinds of plants. 



Thus far I have spoken only of one type 

 of tumor, the common crown gall. Until 

 this winter (if we except hairy root) I did 

 not know of the existence of other types. 

 Now I believe from what I have seen that 

 all the leading types of cancer, viz., (1) 

 sarcoma, (2) carcinoma, (3) mixed tumors 

 and (4) embryomas, occur in plants and 

 that all are due to one and the same organ- 



