Of this international “network” of like-thinking men at the highest level, in Dr. Herzl's day, the student may only make a picture by carefully piecing together significant glimpses and fragments (its existence and concerted actions in our time are plainly demonstrable, as this book in its later chapters will show, from the growing mass of literature).

Make this lower case.
of this international “network” of like-thinking men at the highest level, in dr. herzl's day, the student may only make a picture by carefully piecing together significant glimpses and fragments (its existence and concerted actions in our time are plainly demonstrable, as this book in its later chapters will show, from the growing mass of literature).