Question

which excerpt from Frankenstein best reflects the 19th-century concern that scientists pursue their studies at any personal or moral cost

Answer 1

I hadn’t desired it with an ardor that far exceeded moderation; but now that I had finished, the beauty of the dream vanished, and the breatheless horror and disgust filled my heart

Answer 2

In this excerpt, we can read the conclusion of Victor Frankenstein about science: in the 19th century, scientists pursue their studies at any personal or moral cost:

"With a confusion of ideas  only to be accounted for by my extreme youth and my want  of a guide on such matters, I had retrod the steps of nowledge  along the paths of time and exchanged the discoveries  of recent inquirers for the dreams of forgotten alchemists.  Besides, I had a contempt for the uses of modern natural  philosophy. It was very different when the masters of the  science sought immortality and power; such views, although  futile, were grand; but now the scene was changed.  The ambition of the inquirer seemed to limit itself to the annihilation  of those visions on which my interest in science  was chiefly founded. I was required to exchange chimeras of  boundless grandeur for realities of little worth.

Such were my reflections during the first two or three  days of my residence at Ingolstadt, which were chiefly spent  in becoming acquainted with the localities and the principal  residents  (..)"

When the objective of the science experiments is only the recognition, the need for making something original and spectacular, to be regarded by other scientists the results could be terrible. For example, the creation of the poor monster of Frankenstein story.