By the employment of a soft tube it is possible to determine (1) the existence of an obstruction to the entry of food; (2) the motorial activity and general capacity of the stomach; (3) the chemical characters and digestive properties of the gastric secretion ; (4) the presence of blood, bile, micro-organisms, and of particles of new growth.

(1) Carcinoma of the stomach is accompanied by pain and difficulty of deglutition whenever the disease involves the cardiac orifice or extends into the oesophagus. In such cases the employment of a soft tube not only will determine the existence and site of the obstruction, but will often afford valuable information concerning the condition and character of the growth. In order to obtain the best results the tube should be of moderate size, with an opening about one inch from its point, and should be graduated externally in inches or centimetres. The instrument is gently inserted until its progress is firmly arrested, when the scale at the level of the incisor teeth is read off and recorded. The patient is then made to cough several times, so as to drive any material that may exist above the stricture into the interior of the tube, after which the free extremity is firmly closed with the finger and the instrument quickly withdrawn. Since the average distance between the incisor teeth and the cardiac orifice in an adult man is 16-18 inches (40-47 cms.), the site of the obstruction is readily determined by reference to the scale of measurement; but it must always be borne in mind that a stomach which is contracted by diffuse cancerous infiltration may also prevent the insertion of a tube beyond eighteen inches. The quantity of material extracted varies, according to the severity of the stenosis, from one drachm to two fluid ounces or more, and usually consists of milk or undigested food mixed with mucus and saliva. In reaction it is neutral or alkaline, and it exhibits no digestive power upon egg albumin after acidification with hydrochloric acid. If the morbid growth is ulcerated a small quantity of grumous matter or bright blood may be present, while occasionally the material possesses a disagreeable or fetid odour indicative of sloughing of the neoplasm. On microscopical examination particles of food, epithelial cells, torulae, cocci, and bacteria can always be detected, and in some instances blood or pus cells and even fragments of the growth may be recognised.

(2) In its normal state the stomach in the early morning either is empty or at most contains only one or two cubic centimetres of an acid mucoid fluid, while its motor activity is sufficient to dispose of a full meal within seven hours. Should the pylorus be contracted, however, or the muscular coat of the organ be too feeble to perform its accustomed functions, the food will remain in the stomach for a much longer period. It is therefore advisable in every case to conduct the first investigation in the early morning, when no food has been taken for at least twelve hours. As soon as the instrument has been inserted into the stomach the patient is made to compress the abdomen with his hands and to cough vigorously, when the rise of intragastric pressure causes the evacuation of any material the organ may contain. Should these measures fail to procure the desired result, the nozzle of a glass syringe may be attached to the end of the tube and siphonage started by means of suction. In every case of gastric cancer accompanied by enfeeblement of the muscular coat of the organ a certain amount of undigested food may be extracted in this manner, while in pyloric obstruction the quantity sometimes exceeds two pints. The phenomenon of food stagnation which is thus demonstrated not only establishes the existence of gastrectasis, but constitutes a rough indication of the degree of dilatation of the stomach. This conclusion may be further confirmed by the detection of some article of diet, such as beans, peas, grapestones, or other vegetable matter, which had been eaten by the patient several days, or even weeks, previously.

(3) In order to obtain the most reliable information concerning the state of the gastric secretion, it is necessary to examine the contents of the viscus at the height of digestion rather than during the period of food stagnation. For this purpose the organ is washed out in the early morning, and afterwards the patient partakes of a test meal composed of half a pint of weak tea and a thick slice of bread and butter. At the end of an hour the tube is again passed and the semidigested material extracted. It may usually be observed that the quantity of liquid obtained in this manner equals or even exceeds the amount administered, and that the bread shows little or no signs of digestion. There is also a large excess of mucus, which renders filtration through paper such a tardy process that it is generally advisable to strain through wellwashed butter-muslin. In almost every instance the filtrate is acid in reaction, although when triturated with the decinormal solution of soda its total acidity is found to be much reduced.