XYI. Explanation of Plates I, IT. 



The following abbreviations apply to all plates in which they occur. 



a 



artery. 



I 



lymphoid tissue. 



b.c 



blood cell. 



leu 



leucocyte. 



b.s 



blood sinus. 



ph. 



phagocyte. 



h.s.c 



central blood sinus. 



p m 



pigment mass, 



b.s.jj 



peripheral blood sinus. 



r 



reticulum. 



c 



capsule. 



r.c 



reticulum cell. 



e.c 



endothelium cell. 



s J 



strand of lymphoid tissue 



9-c 



germ centre. 



trb 



trabecula. 



i.m.f 



involuntary muscle fibre. 



V 



vein. 



Fig. 1. Portion of a section of spleen (as seen under a magnification of 50 dia- 

 meters), m.c.a Malpighian corpuscles containing artery; m.c.g Malpighian 

 corpuscles containing germ centre; spl.p Spleen pulp. (Reduced to ^/.^.j 



Fig. 2. Section of typical hœmal gland (as seen under a magnification of 45 dia- 

 meters). The sinus contains blood ceUs in abundance and a few scat- 

 tered leucocytes. (Reduced to ^/o.) 



Fig. 3. Section of a portion of Dog's hcemal lymphatic gland (as seen under a 

 magnification of 105 diameters), s.s small sinus. All sinuses contain a 

 mixture of blood and lymph. (Reduced to ^/.,.) 



Fig. 4. Portion of section of lymphatic gland of pig (as seen under a magni- 

 fication of 50 diameters). The sinuses contain lymph corpuscles only. 

 (Reduced to ^o-) 



Fig. 5. Section passing through the sinus of a hssmal gland of the rat, stained 

 hcemulum and eosin (as seen under magnification of 250 diameters). 

 Showing a vein leading directly from the sinus and other vessels being 

 conducted by lymphoid strands to the general mass of adenoid tissue. 

 ca capillary; e.c.c endothelium cell of capillary, continuous with cell of 

 adjoining sinus; f fat cell;^) t.a.a tunica adventitia of vein, continuous 

 with capsule. 



Fig. 6. A germ centre from a sheep's gland, stained Heidenhain's iron hsematox. 

 and eosin (as seen under a magnification of 1000 diameters), cm cell 

 undergoing kai'yokinetic division ; 1. 1 general mass of lymphoid tissue. 



') The fat surrounding these glands is in the rat not of the ordinary variety. 



