BLOOD AND LYMPH. 573 



Small amounts of hematoporphyrin are also present in urine. It is not 

 without interest that the amount of this substance increases after certain 

 kinds of poisoning, e.g. lead, trional, sulfonal, and in certain diseases of 

 the liver. The urine then has the red color of Burgundy. 



We have now mentioned what is known of the destiny of the 

 blood-pigment in the animal organism, and have become acquainted 

 at the same time with a new, important function of the liver- 

 cells. We must admit that there are still many gaps which must be 

 bridged over with regard to our knowledge of the disintegration of 

 hematin, and there are a great many contradictory results obtained in 

 the study of the final end-product, urobilin, which remain to be 

 explained. 



It might be expected that some insight into the construction of hemo- 

 globin would be obtained if we were able to find out where it is formed. 

 Up to the present time this has not been definitely settled. We are 

 inclined to believe that hemoglobin is formed at the place where the red 

 blood-corpuscles come into existence, but even the origin of these cor- 

 puscles is in doubt. Bone-marrow is chiefly considered in this connection; 

 and in cases of an unusual new formation of the blood-corpuscles, the ex- 

 traordinary activity of the cancellous tissue is apparent, even to the naked 

 eye, by the marked red coloration. It has been asserted frequently that 

 the spleen is also able to produce red blood-corpuscles, but this asser- 

 tion has been contradicted. It has been attempted to decide this 

 question by extirpating the spleen. The operation is withstood quite 

 well by the organism. While some authors have claimed that there 

 resulted a marked diminution in the number of red corpuscles, others 

 were not able to find this the case. Finally, the spleen has been assigned 

 a part in the destruction of the red corpuscles. Unquestionably this 

 last assumption is not well founded. To be sure, the spleen usually 

 contains iron. Experience also teaches us that the spleen is able to 

 capture foreign substances from metabolism and to retain them, and on 

 the other hand, by administering iron salts the iron content of the spleen 

 is considerably increased within a short time, without there being any 

 evidence of a destruction of red blood-corpuscles. At all events, the part 

 played by the spleen, either in the formation or the destruction of red 

 blood-corpuscles, is absolutely unexplained. The same is true regarding 

 the function of the so-called hemal-lymph glands which are joined to the 

 aorta and differ from the ordinary lymph-glands by the fact that the 

 lymph-passages are either missing or incompletely developed. The 

 capillaries from the arteries pass directly into the lymph sinus and 

 into the blood-spaces representing the interfollicular lymphatics, and 

 from thence the veins lead out directly. The hemal-lymph glands occupy 

 anatomically an intermediate position between the ordinary lymph- 



