Sentence:  After * * f and * * f were passed through Dowex-2-chloride twice and <WSD>treated</WSD> twice with healthy sweet clover tissue powder , nonspecific staining was greatly reduced but a disturbing amount of such staining was still present . 
Meaning of the word marked with <WSD> tags:  subject to a process or treatment, with the aim of readying for some purpose, improving, or remedying a condition