The following statement is from the book Concepts of Physics Volume 2, by Dr. H.C. Verma, chapter 41 - "Electric Current through Gases", topic "Cathode Rays", page 343:
Cathode rays are emitted normally from the cathode surface. Their direction is independent of the position of anode.
I found the explanation for the first sentence from the section perpendicular emission of the Wikipedia article on Crookes tube. However, I don't understand the second sentence in the quoted statement. It's said that the direction of the cathode rays is independent of the position of anode. Initially, I thought this statement is incorrect as the negatively charged stream, the cathode rays must get deflected towards the positively charged anode. But after seeing the experimental setup of a Crooke's tube (the one with conical flask) it's seems the direction of cathode rays is independent of the position of anode:
Image cropped from Crookes tube - Wikipedia
One possible explanation, I came up with is: The negatively charged electrons from the cathode experience strong repulsive force from the cathode, due to which they gain very high speeds. Due to this they are not significantly deflected by the anode. But if this is the case, I doubt why we must have an anode inside the discharge tube and carry-on only with the cathode? So I think this kind of explanation is incorrect.
To put my question in a nutshell:
Why is the direction of cathode rays independent of the position of anode?