10 
GRAND DISCOVERIES OF LIFE 
and the expanding early vertebrates there lived in Siluric and 
Devonic times a strange group called ostracoderms, about which 
geologists knew little and biologists nothing. In general aspect 
they resembled somewhat their neighbors the old sea-scorpions, 
but relations were doubtful in the extreme. By some anatomists 
they were classed with the invertebrates; by others with the ver¬ 
tebrates, even Huxley and Lancaster concluding that they were 
very specialized fishes. 
But the old antiquated Ostracoderms were not allowed rest. 
Later examination suggested that they were not true fishes at 
all, but a new and distinct class midway between the fishes and the 
marine scorpions. As such they fully explained the resemblance 
which was known to exist between living arthropods and the 
vertebrates. They proved, indeed, to be the ancestral form which 
developed into true fishes and were descendants from the old 
Cambric Merstomes. This conception established, all the known 
facts of anatomy, embryology and paleontology were soon 
brought into full accord. The ancient sea-scorpions, the ostra¬ 
coderms, and the fishes really represented three successive stages 
in the evolution of the vertebrates. Theoretical bridging of the 
once vast chasm between invertebrate and vertebrate was accom¬ 
plished. 
Nor was fuller testimony of the rocks not forthcoming. With 
infinite patience and perseverance Patten left his biological labora¬ 
tories and turned for the nonce paleontologist. In the Devonic 
rocks of Canada he found in a locality whence some of the Ostra¬ 
coderms had been described, an abundance of exceptionally 
illuminating material. Not only were the external details of the 
forms well preserved but the general character and location of 
many of the principal internal organs made out. With the 
theoretical premises the facts as now disclosed fully agreed. This 
was the most important morphological triumph of the century. 
So, in the humble Devonic ostracoderm Life made its greatest 
stride toward that intellectuality which in eons long after was to 
characterize a reasoning being, and determine the raison d'etre 
of an infinite universe. 
Use of fire is so exclusively the prerogative of the human 
family that man may be said to be distinguished from all other 
animals by the one feature that he alone is a fire-using being. 
Not only is he the only animal which either kindles or uses fire. 
