This work is a thesis by Kathryn Eleanor Browne based on the development of certain tendencies in modern Opera and was submitted in 1907 to the University of Illinois. Browne has endeavored to track the roots, growth, evolution, and improvement of various tendencies in the Opera. Only the form of Opera has been evaluated in this study, and no attempt has been made towards the harmonic breakdown of the various operas. The primary tendencies that have been examined are the dissimilarities concerning: The number of acts employed The number and kind of characters A comparison: of the proportion of orchestral work, overtures, ballets and ritornelli; of solo work and the various voices employed; of recitative, spoken, accompanied, and unaccompanied; of ensemble work, duets, trios, quartets, quintets and sextets; separate from this last, a consideration of the proportion of chorus work mixed and sung by the men and the women alone. It contains research on thirty-four operas, and tables have been prepared to accurately consider these proportions, showing the percentage of the factors described. These percentages were acquired by the precise count of the measures dedicated to the solos, choruses, ensembles, etc.