1. Given the set $N=\{x \mid a+1 \leqslant x<2 a-1\}$ is a subset of the set $M=\{x \mid-2 \leqslant x \leqslant 5\}$. Then the range of values for $a$ is $\qquad$ .
$$
\text { II. 1. }\{a \mid a \leqslant 3\}
$$
$N \subseteq M$ has two cases:
(1) $N=\varnothing$, i.e., $a+1 \geqslant 2 a-1$, which gives $a \leqslant 2$.
(2) $N \neq \varnothing$, then
$$
\left\{\begin{array}{l}
a+1 \geqslant-2, \\
2 a-1 \leqslant 5, \\
a+1<2 a-1
\end{array} \quad \Rightarrow 2<a \leqslant 3 .\right.
$$

Combining, we get $a \leqslant 3$.