480 Professor William Stirliny [March 4, 



100 grammes Ascaris, jilaced in boiled normal saline solution, 

 used per day — 



0*7 gramme glycogen, 

 0-1 „ sugar, 



No fat ; 



and yielded — 



• 4 gramme CO2 



0'3 ,, valerianic acid. 



It would seem that glycogen had split into COo and valerianic 

 acid — 



4 CgHi.Oe = 9 CO, + 3 C.'E.fi^ + 9 H, 

 720 = 396" + 306 + 18/ 



Is it a genuine fermentation ? 



Weinland found that he could express by Buchner's method a 

 substanc-e " zymase," which could split glycogen into CO2 and valeri- 

 anic acid. 



Turning now to respiration in invertebrate animals, and dealing 

 first with those which live in water, let us see some of the contrivances 

 by which this end is achieved. The mechanisms are but means to an 

 end. The ultimate union of oxygen, and the discharge of carbon 

 dioxide with the liberation of energy, occur in the protoplasm of the 

 cell itself. 



There are two distinct processes, and it may be that the oxygen 

 is introduced by one portal and the carbon dioxide got rid of by anothery 

 or it may be that one portal may do for both processes — the letting in 

 of oxygen and the giving off of carbon dioxide. 



Although the principle itself is simple, the variety of mechanisms 

 adopted by nature to secure this double function is remarkable. Let 

 us glance at some of the mechanisms proceeding from the simple to 

 the complex, and first with regard to those animals that live in water. 



Consider the oceanic fauna. It is immense both from the point 

 of view of number and variety. Save insects and certain groups of 

 molluscs, all invertebrates are aquatic. Amongst vertebrates, fishes 

 have aquatic respiration ; and some mammals, e.g. cetaceans or whales, 

 have water as their sphere of existence, though they depend on the air 

 for their respiratory oxygen. 



The evolution from an aquatic to an aerial mode of existence can 

 be traced in the animal kingdom, and may even be seen within limits 

 in the history of certain species. 



Every living cell, animal or vegetable, requires for its continued 

 existence a supply of oxygen, and every living cell exhales carbon 

 dioxide. The exchange of these two gases between the fluids 

 of the body and the outer medium is the process of respiration. The 

 simplest form of respiratory exchange occurs where there is no specially 

 differentiated organ or mechanism for this purpose, so-called diffuse 

 respiration. The whole surface of the organism in a watery medium 

 may be concerned in this respiratory exchange. This is only possible, 



