which was called the zymotic theory of disease;

也就是发酵理论息息相关
that is, that it was a form of ferment--

发酵理论认为疾病
a little bit like Pettenkofer had asserted--

类似腐烂的有机体的发酵
caused by some fermentation of

这一观点和佩腾科弗的
decaying organic material.

断言相类似
Under the right conditions of soil, temperature and moisture,

在合适的土壤气温和湿度条件下
this fermentation would give off a poison into the environment.

发酵过程会向环境里释放出有毒物质
Also quite widespread was the idea of spontaneous generation,

另一个普遍认可的学说是自然发生说
that diseases arose somehow spontaneously

这一观点认为疾病是在特定位置的
in a particular locality,

偶发行为
weren't brought in or imported from the outside.

而不是外部输入
There was a famous experiment about this,

在十七世纪有一个