The answer to this question would be soft agar plate.
The semisolid medium tube is mostly used for containing the specimen. It is hard to examine semisolid medium since the bacteria can grow in the upper part, middle part or even the lower part of the medium. In agar plate, the bacteria always growth in the upper part so it is easier to count the bacteria.
But semisolid can give some more information in determining whether the bacteria is anaerobic by looking for bubble inside the medium. Anaerobic bacteria can do fermentation that will produce air.
C. hypothesis. He is giving a possible answer to the question "why did the celery crisp when placed in water?"
