DIGESTION IN THE ANIMAL SERIES. 217 



length, and weighed it in a delicate balance. In one case 

 the fish was ejected after 23 hours, and in another 32 hours, 

 and in several others about 18 and 20 hours. The parts 

 were folded on each other, and compressed into oval masses 

 which, with the point of a pen, I could unravel easily. In 

 measure they were precisely as I had given them. In 

 weight there was a difference : in one case, 9 grs. were 

 reduced to 5j grs. ; in others, 8 grs. to 5 ; 11 grs. to 5 ; 

 7 grains to 3i. In one piece from which I had expressed all 

 the fluid I could, the decrease was slight, and the food was 

 soon rejected. But in every case the delicate shin of the 

 ventral portions of the mackerel and luhiting were unin- 

 jured. The fine metallic lustre was untouched, and the skin 

 unbroken ; showing that the digestion does not consist in 

 appropriating the substance of the food given, but in express- 

 ing the juices contained therein." 



I dare not pause now to touch upon the many topics 

 which are suggested by the conclusion to which these inves- 

 tigations led me. It will be enough just to note here the 

 progressive complication of the digestive function in the 

 progressive complexity of the animal series. Starting from 

 the simple cell, which draws its nutriment from the plasma 

 surrounding it, by a simple process of endosmosis, we first 

 arrive at the mouthless Actinophrys, or Amaha, which, 

 folding its own substance over the food, presses out such 

 nutriment as it can ; we then reach the Infusory with a. 

 mouth, but without stomach of any kind ; * and the Polype, 



* Nobody now believes in Ehrenbcrg's I'olygaslnca, or many-stomached 

 animalcules. 



T 



