DIGESTIBILITY OF FOOD. 309 



The simplest mode of comprehending this idea will be to under- 

 stand by the expression the facility with which the nutrient fluids 

 are able to prepare the substance for resorption, or the short- 

 ness of the time in which the substance in question undergoes 

 resorption, that is to say, the time at which it disappears from the 

 intestinal tract. Yet how did inquirers formerly endeavour to 

 decide the readiness and rapidity of the metamorphosis of nutrient 

 matters ? The determination of this question was mostly limited 

 to this, that the digestibility of compound nutrient matters was 

 estimated by the subjective feelings which patients or con- 

 valescents experienced after having partaken of them. Even if 

 we do not take into account the innumerable deceptions which 

 must necessarily be liable to occur, either on the part of the sub- 

 ject of the experiment or of the person watching the result, an 

 organism which is not in a state of health, and in which all the 

 functions are not performed in a regular manner, cannot assuredly 

 afford a measure of the greater or less digestibility of a substance ; 

 for the power of a patient to bear one or other article of food 

 must depend upon the nature of his malady. Thus, for instance, 

 it is a priori obvious that one patient will find no difficulty in 

 bearing certain kinds of food, which may induce indisposition in 

 another individual ; and every physician who has made it a point at 

 the bedside to attend to the effects of different nutrient substances, 

 as well as to observe the actions of medicines, must be familiar 

 with innumerable instances of this kind. Experiments of this 

 nature are, moreover, not practicable in the case of healthy persons, 

 since they are not conscious from any sensations within themselves 

 whether digestion is proceeding with slowness or rapidity. It is 

 only in recent times, since we have begun to experimentalise 

 scientifically, that attempts have been made to collect any definite 

 positive facts, with the view of establishing the different digesti- 

 bility of even the most ordinary articles of diet. Of this class of 

 experiments, those of Gosse are the best known ; he possessed, as 

 is occasionally the case, the faculty of swallowing air, and of thus 

 distending the stomach to such an extent as to induce vomiting ; 

 and he employed this peculiar power in order to bring up food 

 which had remained for different lengths of time in his stomach. 

 Spallanzani* introduced perforated tubes or linen bags filled 

 with different varieties of food, through the oesophagus into the 

 stomachs of cats, and observed in this way the time that elapsed 

 before the various articles of food disappeared from the above* 

 * Yersuche viber d, Verdauungsgeschaft Leipz. 1785. 



