Back in 2011 I wrote a post entitled "Wartel's Hum" in which I referenced a book written by Wartel's student Sophia Marquise A. Ciccolini. Her book, Deep Breathing: As a Means of Promoting the Art of Song, and Curing Weaknesses and Affections of the Throat and Lungs, Especially Consumption (1883) was not available online at the time I wrote my post. However, it's now been scanned by the library gods and can be found on VoiceTalk's download page.
Why should Ciccolini's book interest you? There is the Wartel connection for starters. He was a student of Adolphe Nouritt, himself a student of Manuel García père. Then there is the teaching of Ciccolini herself which centers on breathing and its appliccation in singing and matters of health—perennial wisdom that needs to be discovered by every generatation.
Wartel, who was then about 70 years old, and who still often delighted his pupils with his full, rich voice, had a very mysterious and ingenious method which, as he said, was taken from the old Italian masters. He had us sing certain exercises with closed mouth, in order to bring us unconsciously to the end he had in view, viz.: to attack every tone in one and the same place and to employ deep, abdominal breathing. —Sophia Marquise A. Ciccolini. Deep Breathing: As a Means of Promoting the At of Song, and Curing Weakness and Affections of the Thoat and Lungs, Especially Consumption (1883).
What's fascinating about the passage above is the reference to the old Italian school teaching which instructed the student to "attack every tone in one and the same place."
I can tell you one thing: They weren't talking about the larynx!