SPIT

A stream of information about saliva’s host of forms and functions.

Why think about spit? For one thing, the biodiversity of oceans and rainforests may get plenty of notice, but as Batten writes, “you have a diverse natural ecosystem right inside your mouth.” For another, “whether your food is going down (when you’re eating) or up (when you’re barfing), there are five kinds of salivation.” Along with dipping into the biota and biology of spit, venom, and related substances, the author introduces relevant scientists and others, from Ivan Pavlov to baseball spitballer Elwin Charles “Preacher” Roe, as well as a host of animal spitters, including snakes, mosquitoes (“the only creatures that can suck and spit at the same time”), and venomous shrews. Saliva’s roles in both healing and in spreading disease also come in for look overs, and a final chapter gathers up competitive spitting events involving not just watermelon seeds, but also crickets and kudu poop. The lively color stock photos and crudely drawn pen-and-ink figures make an ill-fitting mix but do catch the tang of the narrative. Still, in comparison to Dawn Cusick’s blatantly titillating Get the Scoop on Animal Snot, Spit and Slime! (2016), Batten goes for a more-measured blend of gross and intellectual grist. Human figures are rare, but there is some diversity in the cast.

A lot to digest—but easy to chew, swallow, and regurgitate.