120 STUDENTS HISTOLOGY 



(b) Transverse sections of Malpighian bodies, noting that the 

 vessel is seldom in the center of the nodule. (<?) Nearly longi- 

 tudinal section of Malpighian nodules, observing that the lymph- 

 oid tissue usually follows or surrounds the artery for a short 

 distance only. In many of the lower animals the Malpighian 

 bodies are more sharply marked off from the splenic pulp than 

 in man. 



5. The Splenic pulp. (This will be found in those portions of 

 the section not occupied by structures previously demonstrated ; 

 and wiH be determined by its light color. Review the whole area, 

 and endeavor to differentiate every portion of the lymphoid and 

 pulp -tissue. The staining will have been your principal guide 

 thus far, the pulp-elements appearing in strong contrast by their 

 pink eosin color.) 



(H.) 



6. The structural elements of the capsule, (a) The numer- 

 ous minute lymph-spaces and the imperfect vascular supply. 

 (b) The nuclei of the peritoneal cell covering. (This presup- 

 poses that the section has been selected so as to include the 

 peritoneal investment.) (c) The abundant and closely packed 

 connective tissue, (d) The muscle -nuclei, (e) Cells contain- 

 ing granular yellow pigment. (The quantity varies largely with 

 different specimens.) 



7. The Malpighian nodules, (a) The arterioles very small 

 and apt to escape attention unless filled with blood -corpuscles. 

 (b) Their reticulum. (This will be difficult of satisfactory dem- 

 onstration, unless the section is thin.) 



8. The elements of the pulp, (a) Large flattened cells, the 

 branches forming the meshwork of venous channels. (b) Red 

 blood-corpuscles. (Very numerous, and often broken and dis- 

 torted.) (c) Blood -pigment. (d) White blood-corpuscles. 

 (Some of them may contain granules of pigment, which are 

 composed of the derivatives resulting from the disintegration of 

 hasmoglobin. The destruction of worn-out red blood -corpuscles 

 probably is one of the most important functions of the spleen.) 

 (e) Large multi-nucleated cells, (which are commoner in the 

 spleens of young animals). 



