XXXV11 



Consisting chiefly of Cytogeuous Tissue. 



Cytogenous tissue consists of a sponge-like network of cells, 

 whose meshes are occupied by small rounded cells. Masses of 

 this tissue are found in many parts of the body, especially in the 

 walls of the alimentary canal. Red blood-corpuscles are also 

 thought to be in part formed in certain connective-tissue 

 corpuscles of the embryo, and in the red marrow of bones. 



Placed in the path of the Lymph, elaborating and adding cells 

 to it. 



Examples. Tonsils. 



Thymus. (Hassel's corpuscles derived from alimentary 



canal.) 

 Lymphatic glands. 



Placed in the path of the Blood, elaborating it, adding new 

 corpuscles, and destroying old ones. The lymphatics are here 

 continuous with the blood vascular system. 



Example. Spleen. 



L. 



CIRCULATORY SYSTEM AND BODY-CAVITY 



(=COELOM). 

 Plants. 



The sap of vascular plants is mainly conducted by their fibro- 

 vascular bundles (wood, &c.). The causes of its movements are : 

 the osmotic absorption of fresh material by the roots forcing 

 upwards that already in the plant (= root-force); the evaporation 

 from leaves and other parts drawing upwards the sap below ; th 

 demand for fresh material by growing parts, these abstract from 

 the sap the materials required for their growth, a constant dif- 

 fusion current must take place between the sap deprived of such 

 materials and the sap still containing them. 



Examples showing arrangement of vascular bundles in taxouomic 

 order. 



