Origin of Species Variorum

Comparison with 1869

in the nature of their secretions. In some instances the males alone, in other instances both males and females, have been observed to be thus affected in a slight degree. When the differences are rather more strongly marked, and when both sexes and all ages are affected, the forms would be ranked by all entomologists as species. ↑ But no man can determine for others, even if he can do so for himself, and determine with certainly which of the several phytophagic forms to call varieties and which to call species. ↑ Mr. Walsh ranks the forms which it may be supposed would freely intercross together, as varieties; and those which appear to have lost this power, as species. As the difference in all these cases clearly depends on the insects having long fed on perfectly distinct plants, intermediate links between the several forms thus produced cannot be expected to be found; though formerly such must have existed, connecting the present divergent forms with their common progenitor. The naturalist thus loses his best guide in determining whether to rank such doubtful forms as varieties or species. This likewise necessarily occurs with closely allied organisms, of doubtful value, which inhabit separate continents or distant islands. But when an animal or plant ranges over the same continent or inhabits many islands in the same archipelago, and presents different forms in the different areas, there is always a chance, which is not rarely successful, that intermediate forms may be discovered which shall link together the extreme states; and these are then degraded to the rank of varieties.

Some few naturalists maintain that animals never present varieties; but then these same naturalists rank the slightest differences as of specific value; and when even the identically same form is met with in two distant countries, or in two distinct geological formations, they go so far as to believe that two separate species are hidden under the same dress. The term species thus comes to be a mere useless mental abstraction, implying and assuming a separate act of creation. ↑ It is certain that many forms, considered by highly-competent judges as varieties, so completely resemble species in character, that they have been thus ranked by other highly-competent judges. But to discuss whether such slightly different forms are rightly called species or varieties, before any definition of these terms has been generally accepted, is vainly to beat the air.

Many of the cases of strongly-marked varieties or doubtful species well deserve consideration; for several interesting lines of argument, from geographical distribution, analogical variation, hybridism, &c., have been brought to bear on the attempt to determine their rank. Close investigation, in many cases, will bring naturalists to an agreement how to rank doubtful forms. Yet it must be confessed that it, is in the best known countries that we find the greatest number of forms of doubtful value. I have been struck with the fact, that if any animal or plant in a state of nature be highly useful to man, or from any cause closely

in the nature of their secretions. In some instances the males alone, in other instances both males and females, have been observed thus to differ in a slight degree. When the differences are rather more strongly marked, and when both sexes and all ages are affected, the forms are ranked by all entomologists as good species. ↑ But no observer can determine for another, even if he can do so for himself, ... which of these Phytophagic forms ought to be called species and which varieties. ↑ Mr. Walsh ranks the forms which it may be supposed would freely intercross, .. as varieties; and those which appear to have lost this power, as species. As the differences ... depend on the insects having long fed on .. distinct plants, it cannot be expected that intermediate links connecting the several forms should now be found. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. The naturalist thus loses his best guide in determining whether to rank .. doubtful forms as varieties or species. This likewise necessarily occurs with closely allied organisms, ... which inhabit distinct continents or .. islands. When, on the other hand, an animal or plant ranges over the same continent, or inhabits many islands in the same archipelago, and presents different forms in the different areas, there is always a good chance that intermediate forms will be discovered which will link together the extreme states; and these are then degraded to the rank of varieties.

Some few naturalists maintain that animals never present varieties; but then these same naturalists rank the slightest difference as of specific value; and when .. the same identical form is met with in two distinct countries, or in two .. geological formations, they ... believe that two distinct species are hidden under the same dress. The term species thus comes to be a mere useless .. abstraction, implying and assuming a separate act of creation. It is certain that many forms, considered by highly-competent judges to be varieties, resemble species so completely in character, that they have been thus ranked by other highly-competent judges. .. .. .. .. .. But to discuss whether they ought to be called species or varieties, before any definition of these terms has been generally accepted, is vainly to beat the air.

Many of the cases of strongly-marked varieties or doubtful species well deserve consideration; for several interesting lines of argument, from geographical distribution, analogical variation, hybridism, &c., have been brought to bear in the attempt to determine their rank; but space does not here permit me to discuss them. Close investigation, in many cases, will no doubt bring naturalists to agree how to rank doubtful forms. Yet it must be confessed that it is in the best known countries that we find the greatest number of them. I have been struck with the fact, that if any animal or plant in a state of nature be highly useful to man, or from any cause closely