80 HAECKEL: HIS LIFE, WORK, AND COMPANIONS 
Haeckel devoted himself to popularizing Darwinism, 
to defending it against opponents, and to supplementing 
and extending its doctrine. But he did mere than that. 
He undertook a restatement of biological science, and 
revision of zoological classification on the basis of evolution. 
To that strennous task he brought rare natural gifts, com- 
prehensive, precise knowledge: and what was also essential 
to success, an iron constitution. Bolsche, his biographer 
says: ‘‘ From his splendid physique in early manhood, he 
won at Leipzig a Jaurel crown for the athletic deed of leap- 
ing twenty feet.’? And he humorously adds that the night 
after the contest the friendly host put a pair of dumb-bells 
into Haeckel’s bed, in case he desired to take another spell 
of exercise before morning. 
Darwinism and the labours of Haeckel are so inti- 
mately connected that for a right estimate of his character 
a summary of that theory is relevant and next to indispen- 
sable. A library would be needed to show the ramifications 
of Darwin’s doctrine. Still a glimpse at the leading facts 
on which his theory rests, the order in which these facts 
impressed him, and the chief conclusions he deduced from 
them may suffice. These may be compressed into a few 
sentences. In his early studies Darwin suspected that 
species might be mutable. But, pending due investigation, 
he suspended judgment. Linnseus had conferred a boon on 
“science by his use of combined words denoting genus and 
species to designate certain differences of organic life. That 
method admirably served to distinguish the various mem- 
bers of each family of living things, after the manner that 
each member of a household is distinguished by use of a 
conjoint Christian name and surname. Linneeus, it is said, 
believed that some one species of each genus originated from 
direct creative fiat; but that kindred species of that genus, 
other than such an one, were of secondary origin. But by 
most of his followers every species was held to be immu- 
table, and to have been originated by creat tive fiat. The 
described species of organic life now exceed halt a Fillion ; 
