69 



stomach is incapable of digesting food, secondly whether it 

 is capable of resorbing the products of hydrolysis. 



The preparation after having been filled with the solution to 

 be studied, was put into a shallow watch-glass in some sea water 

 with the oral side up — in order by gravitation to keep the 

 liquid in the stomach — . After various periods of time tests 

 were made for glucose or amino-acids in the surrounding liquid. 



As far as the digestion is concerned, completely positive evidence 

 was obtained. A Fehling's test and a ninhydrin both gave 

 positive results in so many cases that there does not seem to 

 be any reason for doubt as to the capacity of the isolated 

 stomach for digesting food substances. 



As far as the resorption is concerned, I believe that we are not 

 entitled to draw sufficiently justified conclusions from a few experi- 

 ments like these. There are three important possible sources of 

 error. In the first place we do not know how long the stomach 

 actually remains alive; its wall might finally become a dead 

 membrane through which everything passes; in the second 

 place the products of hydrolysis may have escaped through 

 the mouth and thirdly the stomach pouches and the remnants 

 of the ducts may have taken care of the resorption. One fact 

 especially makes me doubtful, i. e. that it always took a long 

 time for the substances to make their appearance.' 



The anatomy and histology of the radial ducts does not 

 give us much information either. In the snails the anatomical 

 relations are such that the food masses are forced to 

 enter into the „liver" (see Biedermann and Moritz" 9)). 

 The same thing is true for the crawfish (see Jordan 64)). 

 Here we do not find anything of the kind. I have fixed some 

 of these ducts including a little piece of the stomach and of the 

 radial sacs in acetic-alcohol and cut them up in a serial section. 

 Though these sections were very poor, partly maybe on account 

 of the fixing fluid, they showed at least this, that there is no 

 particular device for forcing the food into the stomach neither 

 is there a filtering apparatus („Reusenapparat") The ducts are 

 simply hollow tubes, leading streight from the stomach into the 

 radial sacs. The lining epithehum is ciliated everywhere : possibly, 

 these cilia by their movements account for the transport of the 

 food from stomach to radial sac. In the sections moreover 

 small pieces of organic material, stained with the eosin employed 

 to color the sections, were seen lying within the tubes. To me 

 they looked like food particles on their way from the stomach 

 to the radial sacs. 



If all these data do not give us any positive evidence whether 

 or not the radial sacs are organs of resorption, there are others 

 however which to me are absolute proof for my thesis that 

 they have this function. 



I have fed starfishes on various substances and I could observe 



