GROWTH OF A TRANSPLANTABLE TUMOR IN MICE S21 
The writer, in collaboration with Tyzzer (16), has tested the 
behavior of another tumor—a carcinoma of the Japanese waltz- 
ing mouse (J.W.A.). Here the successful growth of tumor 
implants was found to depend upon a complex of some twelve or 
fourteen independently Mendelizing factors introduced by the 
Japanese race. The presence of all these factors as a complex 
even in a single dose is enough to give a favorable reaction to 
the tumor implant, resulting in its continued growth. In the 
gametogenesis of animals possessing the complex in a single dose, 
the factors forming the complex for susceptibility are distrib- 
uted according to the random segregation of the Mendelian prin- 
ciples. Whenever a gamete is formed with any one of the fac- 
tors of the complex missing, it does not produce a susceptible 
individual unless it meets in fertilization another gamete in 
which the missing member of the complex is carried. 
The idea advanced by Loeb, then, namely, that intermediate 
results are obtained, in the progeny of animals with different 
individuality differentials, is probably due to the fact that not 
only his implants, but his host stock were variables. It would 
be nearer the truth to say that most individuals in gametogenesis 
form gametes differing considerably from each other in the ge- 
netic factors underlying the individuality differential which they 
carry. When a new zygote is formed, its individuality differ- 
ential as a host is dual. It has the power of supporting growth 
of any tissue which in its zygotic formula carries in a double dose 
either of the identical factor complexes which the gametes con- 
tributed by each of its parents carried in a single dose. 
For example, let us suppose that the factor complex under- 
lying the individuality differential contributed by the sperm of 
the male parent of individual X was factors A™B™C™ and by the 
egg of its female parent A‘B‘C’. Individual X is of the formula 
A™A‘B=BiC2C!. It could support the growth of tissues of 
formulae A™A™B™B=CC™ or AfA‘BIBICC! or A™A‘B™B'C=C;, 
the latter being an individual identical with itself as regards the 
factors under consideration. 
The critical point is that the host can utilize as its individuality 
differential either a combination of both the factor complexes 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 31, No. 3 
