433 



The second theory is that proposed by Putter ('OS). He holds thai 

 the iiutritioii or many aquatic forms is essentially different from that of 

 land animals. He shows that water contains large amounts of carbon com- 

 pounds in solution and demonstrates experimentally that this is the source 

 of nutrition for a si)onge. Suheritcs (lomuitcula and a holothurian {Cii- 

 cumaria gruhel). In this paper and two subsequent ones, he extends his 

 theory to include representatives of every phylum of aquatic animals. 



Possibly foreseeing the difhculty offered by the fact that in general, 

 waste compounds of animals are less complex than their food, he sug- 

 gests that a photochemical process may talie place in aquatic animals, 

 analogous to that of chlorophyl bearing plants. "Ob die gelosten Stoffe, 

 die den niederen Tieren als Nahrung dienen, soviet Energie enthalten, dasz 

 der Abbau durch Spaltungen imd Oxydationen allein hinreicht, um den 

 Energiebedarf der Tiere zudecken, oder ob hier in einer weiteren Analogie 

 mlt dem StofCwechsel der Pflanze strablende Energie ausgenutzt wird, um 

 durch piiotoehemische Prozesse aus den aufgenommenen gelosten StofCen 

 Substanzen von hoherem Energiegehalt herzustellen, das ist eine Frage von 

 so hoher prin^ipieller Bedeutung, dasz, die wenigen Erfahrungen, die zu 

 ihrer Erorterung gegenwartlg beigebracht werden konnten. nielit hin- 

 relchend zur Entscheidung sind." 



With the exception of Simocephalus veteJIus, the methods of Piitter 

 have not been applied to species found in this pond. Wolff, '09, was able 

 to show that Simoccplialua veteJIus could develop in a medium free from 

 nutrition in the form of solids (geformte Nahrung K 



Without denying the possibility that aquatic animals derive some food 

 from the water by direct absorption of nutrient solutions, it may be stated 

 with certainty that the higher animals of this pond for the most part 

 utilize solid food. This statement is based on observations on feeding and 

 the examination of alimentary tJ'acts. 



In this discussion of Ihe food relations of these animals, I shall ignore 

 Piitter's alternative. If it be subsequently proven that the ingestion of 

 food is merely incidental, it will also establish their complete independences 

 so far as food relations are coucernedi 



I have tried to express in the accompanying diagram some of the im- 

 portant food relations between the organisms of the pond. These relations 

 are very complicated because of the omniverous habits of some of the 



[2,S— 26988] 



