224 WILLIAM RAY ALLEN! 



Mitra (I.e.) was the first to recognize clearly that the crystal- 

 line style may meet several needs. The fact that it is dissolved 

 when food is wanting, and that in solution it may be taken up by 

 the blood, leads to the conclusion that it is (so far as it goes) a 

 reserve of nutriment. Furthermore, the work of Mitra and 

 others has shown that it bears enzymes capable of furthering 

 starch digestion. Dr. Scott Edwards has kindly checked over 

 this matter for me, with confirmatory results. Insofar as suitable 

 food is brought into contact with it, it is a means of supplying 

 digestive ferments. 



Nelson (I.e.) has shown very well that the rotation of the 

 crystalline style against the " gastric shield "in the stomach shreds 

 the dissolving end so as to form a brush. The rotation of this 

 brush sweeps the food into the proper ciliated channels, aids in 

 dissolving the food out of the mucous masses in which it reaches 

 the stomach, and acts as a substitute for peristalsis in mingling 

 food with the digestive fluids from the liver, etc. It might have 

 been pointed out that these movements afford a ready means of 

 bringing the contained enzymes of the style into thorough contact 

 with the food. 



Since the style actually accomplishes all these things, we can 

 not choose any one of them as the function for which it was 

 designed. We cannot assert that the style is exactly adapted to 

 perform any one of them, or that it is the function which it has 

 always performed in ancestral forms. If such were the case one 

 might expect to find somewhere in the more primitive existing 

 species a style little changed from the ancestral condition. But 

 the Najades have taken to fresh water, and as a result have be- 

 come profoundly modified in life history, ontogeny, and structure. 

 While the crystalline style has shown as little structural change as 

 any organ, it is not improbable that its relation to the organism 

 as a whole, to metabolism, has suffered changes of which we know 

 nothing. 



Nelson suggests a further function of the style sac, that of 

 returning undigested material from the intestine to the stomach, 

 to prevent the loss of food. In Modiohts, which undergoes a 

 periodic cessation of feeding and dissolution of the style, the 



