Experiments with other Mammals III 
cases the Mendelian expectation. Crampe found that when 
wild gray rats, Mus decumanus, were bred to albinos, the off- 
spring (#*) were of two kinds, viz. either (I) gray like the wild rat, 
or (II) gray with white marks. If the former (I) were bred inter 
se, the following types appeared : — 
Self-gray. 
Gray with white marks. 
White and gray. 
White (albino). 
Black-and-white. 
Black with white marks. 
Black without marks. 
OD eS Goa wl 
If the other group of offspring (II) was used, z.e. inbred, all of 
the preceding types except 3 (white and gray) and 5 (black-and- 
white) were produced. 
Bateson states that the great variety of types that appear here 
is difficult to interpret, but that such occurrences are by no means 
uncommon. He suggests that two classes of germ-cells may 
be present either in the albinos or in the wild gray rat. 
The albino is recessive to all the other six types, as shown by 
crossing these with albinos. The extracted albinos bred inter 
se, whatever their origin, gave only albinos. In this connection 
Crampe makes another statement of interest. Albinos that 
‘had been bred true for several generations behaved differently 
from extracted albinos. The former albinos were simply re- 
cessive on being crossed with colored rats, while the extracted 
albinos gave a mixture of ancestral types when crossed with 
colored types. The result appears to be similar to Cuénot’s 
with mice where the ancestry of the albino appears as a factor 
in the product. 
On breeding inter se each of the seven types given above (F;), 
Crampe found that the offspring (F,) belonged to the following 
types : — 
Type 1 might give types I 2 4 
Type 2 might give typesI 2 3 4 
