XXXIX 



The circulation of the Lymph is mainly due to the same causes 

 as those of the blood in the veins, with, in addition, the suction 

 action of the venous blood where that fluid rushes by the orifices 

 by which the lymphatics open into the veins. 



In some animals (e. </. Frogs) the lymphatics have muscular 

 contractile chambers (lymph-hearts) which assist in propelling 

 the lymph. 



Examples of the circulatory system arranged in taxonoinic order, 

 with division into anatomical groups. 



Serous cavities might be placed here. 



Blood-purifying and Sound-producing Organs 



IY1. 

 RESPIRATORY SYSTEM. 



Carbon dioxide, the common waste-product of tissue change, 

 and of the decomposition and oxidation of carbo-hydrates (starch, 

 sugars) and hydro-carbons (fats), is removed from the organism 

 either at the non-specialized general surface, or by more or less 

 special respiratory organs. At the same time that C0 2 is given 

 out Oxygen is absorbed. 



Plants. 



The respiration of Chlorophyll-containing plants when exposed 

 to light is masked by the C0 2 being used as a food-material 

 the C0 2 being decomposed, the carbon used in the formation of 

 starch (C 6 H 10 5 ), and the oxygen given out. In the dark CO^ 

 is given off. There are no special organs for respiration. 



Animals. 



In Water. The necessary special surface for respiration in 

 water is generally in the form of fringe-like projections (e. </. 

 Branchiae, Gills). 



Examples taxonomically arranged. 



