BIOGRAPHICAL SKETCH lxill 
character arise as a variation de novo, or as a progressive modifi- 
cation of a pre-existing character? If de novo, did it spring 
suddenly forth, with some decisive advantage in the struggle 
for existence? Or did it-appear as one of many minute changes, 
and by some happy chance get a start that gave it the lead in 
future development? In other words, did it begin as a discon- 
tinuous variation, sport, or mutation? Or did it arise cumula- 
tively, as a continuous development? If it originated by modi- 
fication of an earlier character, was it at first a sudden, sport-like 
departure? Or was it a slow and continuous transformation, 
of a progressive or retrogressive nature? 
“Then we come inevitably to the deeper question, which natural 
selection only partially penetrates—the question how variation, 
multifarious and undirected, without the aid of design or a de- 
signer, can advance to such definite and wonderful achieve- 
ments as specific characters.”’ 
Whitman’s devotion to the task of learning a specific character 
knew no bounds; it heeded neither time, personal sacrifice, nor 
the difficulties which the ensemble of life processes creates when a 
particular process with which the biologist would become familiar 
is examined. But, he was ever ready and eager to attend to 
each and every perturbation of the system, from whatever 
extrinsic source, if its analysis might lead directly or indirectly to 
a better measure of realities in his own main sphere of study. 
It thus happens that along the pathway which he has blazed 
into the central problems of evolution are to be found many 
discoveries in the fields of instinct, animal behavior, fertility, cor- 
relative variation, the nature of sex, etc. 
Having selected color-pattern in pigeons as supplying a satis- 
factorily small group of specific characters easily accessible to 
study, he first set about determining which patterns are the more 
primitive and which the higher and more recent ones, the facts 
being determined through a most painstaking search for the con- 
vergent testimony of the most various kinds of evidence. Here 
his uncompromising ideal of an intensive and extensive study 
of a character, his own exceptional mastery of the broad field of 
zoology, the eighteen years of unbroken and devoted study that 
