Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: May 14, 2025
To these writers, then, the doctrine of final causes for rudimentary organs was a piece of mystification and an absurdity; no less fatal to any such doctrine were the processes of embryological development. It was plain that the commonly received teleology must be given up; but the idea of design or purpose was so associated in their minds with theological design that they avoided it altogether.
I regret that I am unable to pursue this subject much further; but there is one point I should mention. In Harvey's time, the microscope was hardly invented. It is quite true that in some of his embryological researches he speaks of having made use of a hand glass; but that was the most that he seems to have known anything about, or that was accessible to him at that day.
It is probably best, as urged by several writers, that the life-like illustrations, some of them photographic, in books of human anatomy be kept away from boys of early adolescent age. The embryological facts of human biology are very impressive to boys and young men who know little of science.
Many embryological investigations were performed during the eighteenth century, but most relate to the controversy regarding epigenesis and preformationism as the true expression of embryonic development. Withal, the seventeenth-century embryologists, and particularly the embryologists of seventeenth-century England, had contributed much to the progress of the discipline.
For, as I have recently remarked in regard to the members of each great kingdom, such as the Vertebrata, Articulata, etc., we have distinct evidence in their embryological, homologous, and rudimentary structures, that within each kingdom all the members are descended from a single progenitor. When the views advanced by me in this volume, and by Mr.
It would require an amount of details that would be tedious to many of my readers, were I to add here the evidence to prove that the embryological development of these animals, so far as it is known, and their geographical distribution over the whole surface of our globe, show the same correspondence with the other three series.
To discuss embryological thought in seventeenth-century England is to discuss the main currents in embryological thought at a time when those currents were both numerous and shifting. Like every other period, the seventeenth century was one of transition.
We see why certain characters are far more serviceable than others for classification; why adaptive characters, though of paramount importance to the being, are of hardly any importance in classification; why characters derived from rudimentary parts, though of no service to the being, are often of high classificatory value; and why embryological characters are the most valuable of all.
The Selachians resemble higher Vertebrate types not only in the small number of their eggs, and in the closer connection of the young with the mother, but also in their embryological development, which has many features in common with that of birds and turtles.
"The results," he adds, "of these two methods of study complete and control each other." In all his subsequent researches indeed, the history of the individual in its successive phases went hand in hand with the history of the type. He constantly tested his zoological results by his embryological investigations.
Word Of The Day
Others Looking