Does the one down bow mean all the notes are down bows?
Or, all the notes are down up down up...bows starting on down?
Unless slurs or bowing markings indicate differently, standard articulation changes bow direction every note. In the complete absence of bowing directions, the player needs to cater for himself, usually by making down strokes preferably fall on the principal rhythmic accents.
Down bow on one note show that that single note is supposed to be played down. The rest of the notes are up to you as a player to select. Generally, you would play the example 57 alternating between up and down. If the composer wants you to play all notes down bow, it would be indicated with a slur. Or possibly with reapeated down marks, indicating a more accented playing.
Other answers express the standard notation interpretation for modern editions of western string music.
This is a another case : a series of short expressive exercices for (young) cello beginners. The title has as much weight as the bowing direction and the need to contrast with the previous exercice and the next one. If you are studying by yourself, do it in the manner that express best what you understand of the title. It can be a series of (light) and slow (lament) down bow strokes for a bar, etc. If you have a teacher, just discuss this with him/her and write with a pencil what is the best for your training and the piece so that you are consistent in the way you practice it.