Close listening to this selection reveals two violins--and also reveals doubts as to how many reedmen are on this selection.
One hears nothing on this side that suggests the presence of more than one saxophone. This would put the instrumentation as trumpet, trombone, alto sax, two violins, piano, guitar (possibly a tenor guitar), tuba and drums.
If it's an alto sax, then it is not likely to be Merle Johnston--his usual "axe" was tenor sax.
Two other Jack Miller records worth catching are "Singn' In The Rain" (with a tasty muted trumpet solo), and "The Moon Is Low" (with ferocious muted trumpet work suggesting the best of Tommy Dorsey on that instrument, as well as a bass sax solo by Adrian Rollini).
Jack Miller began recording for Harmony in 1928, soon after they began recording some of their popular vocal discs by the electrical process. Most of his early discs--some of which appeared as by "Fred Waters"--had piano or piano-violin accompaniment. His 1929-1930 sides had "The New England Yakees", a name which suggests that they were trying to compete with Rudy Vallee over at another label.
Most of the 1930-31 sides revert to piano backing, while a couple of Columbia releases in 1931-32 have discreet small orchestras drqawn from Ben Selvin's call-list.
His last appearance as a vocalist appears to be "Morning Noon and Night', a vocal refrain with Ben Selvin's orchestra, cut for "royal blue" Columbia in the summer of 1933.
A "Jack Miller" shows up as Kate Smith's bandleader. I wonder if it's the same chap.