110 Experimental Zovlogy 
erations, however, these characters appear to follow the ordinary 
Mendelian rules of segregation and gametic purity.” Hurst 
calls attention to the similarity of these results to those of Cuénot 
with spotted mice. The results are in agreement as far as the 
marked coat is a unit-character following Mendelian lines, and in 
so far as it may be carried by albinos in a latent state. The two 
results differ in that the marked coat in mice is completely re- 
cessive to uniform coat, while the Dutch markings in rabbits are 
neither dominant nor recessive at first, but give variable hybrids. 
Castle has made a few experiments with rabbits, but the re- 
sults gave little that was new in principle. ‘A cross between 
two different types of albino rabbits, Himalayan and pure white, 
shows imperfect dominance of the Himalayan character in the 
offspring, but complete segregation among their gametes.” 
Long-haired rabbits bred to short-haired individuals give off- 
spring with short hair. When rabbits with ears of different 
length are mated, the offspring have ears intermediate in length. 
In this character, blending appears to take place, and neither 
dominance nor segregation. 
Experiments with Rats 
Rats have been used much less than mice, and the results seem 
to be more complicated. Crampe has published the results of 
a large number of experiments, extending over ten years; but as 
ihe experiments were made before the importance of Mendel’s 
theory was appreciated, it is difficult to interpret from this point 
of view the data obtained. No more striking instance could be 
given of the insight into cross-breeding experiments furnished 
by Mendel’s law than a comparison of the work before and after 
this period. Confused and irregular as the earlier results appear, 
they arrange themselves into orderly groups in the light of this 
law. It is, of course, difficult now to show in all cases that Men- 
del’s law unravels Crampe’s results, since the records are often 
incomplete on important points, where further tests are requi- 
site to interpret the result. Nevertheless Bateson’s analysis 
of Crampe’s data indicates that the outcome shows in many 
