In tall thin columns of fairly small print (considering his kiddie-cute style), Selfridge discourses on the subject of MUD--the word set in caps wherever it occurs. First of all MUD looks, stirs, plops, and smears just like Chocolate Pudding but you can tell the difference by tasting--and you can tell MUD from Cement by waiting to see if it hardens. MUD has many uses, silly and practical. Where to find it is more often a question of when than where. Life started in MUD and clams and microbes live in it now. And you can do your friends a favor by sending them MUD kits--dirt for city dwellers, water if they live in deserts, both if they have access to neither (though ""I can't think of where they might be""). Far too coy and whimsical for most kids, it all seems to be aimed at some hypothetical moppet of no consistent age.