In this chapter, we rejoin Logan and Jack on their trip to Emerald City, where they meet the Scarecrow. Ozma is taking a short break from the comic till Chapter 8.
The Scarecrow isn't the first adult Dorothy & Toto meet in Oz, but he is the first responsible adult, being the only one to object to a child and puppy making a long, dangerous journey all alone.
Toto here is usually depicted as a Cairn terrier, but in Yellow Brick Ramble, he's a Boston terrier. John R. Neill drew him as a Boston terrier in Road to Oz and Emerald City of Oz and I loved what a silly little guy he was in those books!
And naturally, Dorothy needs a Boston terrier on hand so that she can be in a Boston marriage with Ozma when she's older.