No. 572] 



473 



There is an obvious tendency for the spots to become 

 arranged in longitudinal rows, and intermediate stages 

 may be found in which they coalesce to form broken lines. 

 There is little doubt that the complete white stripes 

 occurring in part of this pattern were formed originally 

 through the coalescence of rows of white spots. In the 

 tapir a somewhat similar spotted pattern is found in 

 the young, while the adult Malayan tapir has lost the 

 shoulder and side patches, producing thus a white -bodied 

 animal, pigmented to the back of the foreleg and on the 

 buttocks and hind legs. Among the ground squirrels 

 (('it ill us) a beautiful series can be picked out showing 

 the transition from a uniform grizzled mixture of ticked 

 hairs to indistinct spotting, then rows of white spots, and 

 finally broken and complete longitudinal stripes. The 

 production of these stripes I believe to be due, not to the 

 development of breaks between the primary pigment 

 patches, but to the action of a factor which is the negative 

 of the so-called "English" marking in rabbits, so that 

 instead of the development of seat tend small pigments 

 spots there are formed, instead, spots without pigment. 

 That it is possible to evolve a striped pattern from spots 

 through selection, I have no doubt, and indeed, it is gen- 

 erally believed. On the other hand, it is quite possible 

 that the converse may happen, and spots result through 

 the breaking up of stripes. According to the experiments 

 of Professor Castle and Dr. MacCnrdy, however, it seems 

 to be a difficult matter to fix a given marking by rigid 

 selection, yet it must be admitted that a few years' work 

 even of careful breeding is nothing in comparison with 

 the age-long selection that may have been at work on the 

 species. That it is a difficult matter to produce a given 

 pattern is further evidenced by the fact that in many 

 species in which white markings regularly occur as part 

 of the pattern, these are subject to great individual 

 variation in their extent, showing that they are even yet 

 not wholly definite. 



It was formerly urged against evolutionary doctrine 



