28 Th. Lewis, 



Aves. In the fowl the sinuses and lymphoid tissue are considerably 

 mixed, and are not so easily distinguished from one another. The 

 former are filled with nucleated blood corpuscles, and here and there 

 phagocytes, crowded with pigment or containing several red cells, are 

 met with. Quantities of pigment in a free state are also seen in the 

 adenoid tissue, particularly towards the margins of the sections. 



3. Head Mclney of Fishes. 



I have examined many species of teleostean fishes including Hypo- 

 glossoides limandoides, Trigla lyra, Salmo salar, Rhombus laevis, 

 Pleuronectes flesus, Cyclopterus lumpus, Esox lucuis, Molva vulgaris 

 and Coitus gobio. In some of these the structure of the head kidney 

 (pi. II. fig. 10), consists of adenoid tissue pervaded in many places 

 by a definite blood sinus, containing closely packed nucleated blood 

 cells. The adenoid tissue consists of numerous leucocytes contained 

 in a dense reticular meshwork, and is frequently marked off from the 

 sinuses by an irregular endothelium. In a few, little adenoid tissue 

 is present in the head kidney, the organ having the appearance of 

 a large blood sinus with a dense reticulum. This is well seen in 

 Rhombus laevis and Pleuronectes flesus. In others lymphoid tissue 

 forms the bulk of the gland, and only a few very distinct sinuses 

 are present, e. g. Hypoglossoides limandoides. 



Acipenser sturio is the only ganoid which has been examined. The 

 head kidney consists chiefly of adenoid tissue with here and there 

 small indefinite blood sinuses containing nucleated corpuscles (which 

 were also found in the lymphoid tissue). 



No phagocytosis has as yet been observed in these head kidneys. 



VII. Vascular supply of the hsemal glands of the rat. 



Little attention has been paid to this important part of the 

 anatomy of the hgemolymph glands. Drummond devoted a paragraph 

 to the circulation, but he states that no good specimens were obtained 

 in the dogs which he injected, as he could not distinguish haemal 

 lymphatic, from lymphatic glands, after the injection. His description 

 was based upon an examination of serial stained sections. This 



