338 BOTANICAL GAZETTE [OCTOBER 
thus produced are covered with abortive leafy shoots or with flower shoots if a 
flower incept has been disturbed. On tobacco plants these teratoid tumors 
may give rise to secondary tumots similar in nature. These daughter tumors 
are connected with the parent growths by tumor strands which are quite 
different in structure and location from those occurring in galls of the first 
two classes. The tumor strands heretofore described were found in the Paris 
daisy. They arise in the region of the primary xylem and consist of par- 
enchyma tissue. The new tumor strand found in the tobacco occurs in the 
cortex. It consists of a concentric bundle with the xylem surrounded by the 
phloem. The daughter tumors arise at mocha along the strand and often 
have all i Aue mics of the parent tum 
st case, even more remarkable, ca when the young leaves of 
tobance foie are infected with the crown gall organism. From such infec- 
tions on the midrib and lateral veins tumors arise which produce leafy shoots. 
These tumors the author regards as akin to teratoid tumors in animals. The 
fact of their development is another proof that any plant cell not fully matured 
may retain the capacity for developing the whole organism 
n another paper,‘ written for medical readers, the salsioet of crown gall 
is discussed in its relation to the problems of human cancer. The general 
resemblances in mode of growth, cell multiplication, occurrence of tumor 
strands, and production of secondary tumors in the two classes of growths are 
pointed out. The materials presented in this paper are essentially those of 
earlier papers, together with the new facts of the paper reviewed above. The 
phenomena, however, are described in greater detail, and considered boa special 
reference to their bearing on animal pathology. Here, as in other cases, the 
author relies mostly on numerous excellent photographs for the vheacuratien 
of his evidence. 
n explaining his standpoint with reference to the bearing of his work on 
the problems of animal cancer, the author makes no claim that the causal 
organism of the crown gall has any relation to human cancer. It is pointed out, 
however, that this organism induces in plants a set of phenomena which have a 
st g parallel in the manifestations of animal cancer. Such phenomena are 
the growth without function shown by gall tissue, the persistently embryonic 
character of the proliferating cells, the lack of orderly differentiation of the 
tumor tissues, the existence of tumor strands giving rise to daughter tumors 
repeating the structure of the parent gall, and the occurrence of galls resembling 
embryonic teratoids. It is further pointed out that in the crown gall the cell, 
although apparently possessing invasive capacity, is not itself the parasite, as 
4SmitH, Erwin F., Studies on the crown gall of plants; its relation to human 
cancer. Jour. Cancer Reseuich 1:231-258. pls. 1-25. 1916. 
sIt appears that the embryonic tissue of the gall to a certain extent pushes in 
among the cells of the sound tissue, a phenomenon which distinguishes this gro wth 
from other plant galls induced by fungous 0 ranimal parasites. The mode of progress 
