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Genera and species are, at the present time, for a large part artificial, or stated more correctly, conventional groups. Every systematist is free to delimit them in a wider or in a narrower sense, according to his judgment. The greater authorities have as a rule preferred larger genera, others of late have elevated innumerable subgenera to the rank of genera.
He divided machines into their genera, subgenera, species, varieties, subvarieties, and so forth. He proved the existence of connecting links between machines that seemed to have very little in common, and showed that many more such links had existed, but had now perished.
From rubbing shoulders with scientists in our little universe by the Botanical Gardens, the boy had come to know a thing or two. In Conseil I had a seasoned specialist in biological classification, an enthusiast who could run with acrobatic agility up and down the whole ladder of branches, groups, classes, subclasses, orders, families, genera, subgenera, species, and varieties.
"And note well, even when one has grasped all this, one still knows next to nothing, because these families are subdivided into genera, subgenera, species, varieties " "All right, Conseil my friend," the harpooner said, leaning toward the glass panel, "here come a couple of your varieties now!" "Yes! Fish!" Conseil exclaimed. "One would think he was in front of an aquarium!"
Following this line backward or downward we reach another apparent mutation-period, which includes the origin of the group called Oenothera, with a large number of species of the same general type as the Onagra-forms, Still farther downward comes the old genus Oenothera itself, with numerous subgenera diverging in sundry characters and directions.
Chief among them were specimens of that dreadful cartilaginous genus that's divided into three subgenera numbering at least thirty-two species: striped sharks five meters long, the head squat and wider than the body, the caudal fin curved, the back with seven big, black, parallel lines running lengthwise; then perlon sharks, ash gray, pierced with seven gill openings, furnished with a single dorsal fin placed almost exactly in the middle of the body.
And we are led to this conclusion, which has been arrived at by many naturalists under the designation of single centres of creation, by various general considerations, more especially from the importance of barriers of all kinds, and from the analogical distribution of subgenera, genera, and families.
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