It has been demonstrated that protein digestive enzymes in the digestive tract of octopus, Octopus vulgarts CUVIER, are mainly secreted by the liver and pancreas. In the previous paper, the author suggested that the posterior salivary gland enzyme plays an important part in protein digestion. In order to confirm whether the protein digestive enzyme originates in the posterior salivary gland or not, a few experiments were carried out using an octopus which had undergone an operation to stop the saliva secretion from the gland.
The results may be summarized as follows: there are remarkable differences between the experimental group and the control group in (a) the state of dietary protein remaining in digestive tracts, (b) the proteolytic activity of digestive juices and (c) the proteolytic activity of posterior salivary gland extracts.
From the results described above, it is evident that the greater number of protein digestive enzymes in the digestive tract originate from the posterior salivary gland and largely contribute to digestion.