It has been further shown[90] that loops of intestine entirely removed from the body may be caused to secrete a measurable quantity of fluid by immersing them in certain purgative solutions, especially those containing BaCl_{2}. Other solutions such as pure m/6 NaCl do not cause this secretion, although active peristaltic movements go on in NaCl. In this case the secretion must be entirely independent of the blood pressure. Pilocarpine also in the salivary gland causes an enormous increase in the secretion, without raising the blood pressure in the carotid. It is certain from these facts that in many glands secretion is quite independent of any change in blood pressure; and it seems probable that such changes must play a very subordinate part in the secretion of fluid from the intestine. On the other hand, it is to be noted that in many instances muscular and secretory activities are controlled by the same conditions. There seems to be a common factor in the production of the two functions. Saline purgatives produce not only muscular activity, but also increased secretion; and calcium and magnesium are capable of inhibiting both. Atropin also quiets the movements of the intestine, and at the same time is conspicuous in suppressing the secretion. Section of the splanchnic nerves causes not only increased muscular movements, but an increased secretion of fluid in the intestine. These instances could be greatly increased in number. From them it seems that something exists in common in muscular movements and in glandular activity. What first suggests itself is that the gland cells themselves are made to contract rhythmically by the various conditions which cause rhythmical contractions in muscle. That the stimulus for this must be greater in the case of secretion is shown by the fact that in the intestine peristaltic movements may be maintained in a solution (m/6 NaCl) in which no secretion takes place. It seems not at all improbable that one factor in the production of secretory activity is dependent on a property of the gland cell closely related to muscular contractility.