556 PHYSIOLOGY CHAP. 



the nucleus or its atrophy and reabsorption. We have seen, 

 however, that this theory was contradicted by microscopical 

 observations of the mobile elements of the splenic pulp, among 

 which there are normally no erythroblasts nor other transitional 

 forms between leucocytes and erythrocytes. On the other hand, 

 the observations of Vulpius show that after at most nine weeks 

 after spleuectomy it is impossible to recognise any difference 

 between the blood-corpuscles of normal and those of a-splenic 

 animals, showing that the lyniphapoietic or haemapoietic function 

 of this organ is readily replaced by either the lymphatic glands 

 or the bone marrow. It is apparently in this sense that we should 

 interpret the more recent negative results obtained by Paton and 

 Gulland, and Fowler, as above cited. 



Hypertrophy of the lymphatic glands after spleuectomy has 

 been repeatedly observed on animals as well as man ; but the 

 effect is not constant, nor is it of long duration, which leads one to 

 suppose that it is the result of the operative procedure. Even 

 without any striking hypertrophy, however, it may be assumed 

 that the lymphatic glands, which are exceedingly numerous, are 

 capable of vicariously assuming the lapsed functions of the spleen. 



Bone marrow sometimes seems to contain a large number of 

 haematoblasts after splenectomy (Litten and Orth, Emelianow) ; 

 in a-splenic rabbits and guinea-pigs it contains more iron than in 

 intact animals of the same age (Tedeschi, 1899). This functional 

 substitution is not, however, always apparent, nor in any case is it 

 indispensable, since in fishes which have no bone splenectomy is 

 supported without any perceptible alteration of the blood-corpuscles 

 (Pouchet, 1878). 



Certain observations exist which tend to show that the functions 

 of the spleen can be partly taken on by the liver. Maggiorani 

 (1862) stated that the weight of the rabbit's liver in splenectoniised 

 rabbits exceeded that of intact rabbits by about f ; Montenovesi 

 (1893) describes a clinical case of hypertrophy of the liver con- 

 sequent on splenectomy ; lastly, Tedeschi (1899) has recently 

 shown that the liver of the a-splenic rabbit contains a larger 

 average amount of iron than the liver of intact rabbits, young or 

 old. Still these facts do not seem to us sufficiently conclusive to 

 admit of our assuming that the liver undergoes such modifications 

 as would enable it to resume the haeniopoietic functions which it 

 performs during the embryonic life. The increase in volume and 

 weight of the liver after splenectomy, as also the increased wealth 

 of iron, may depend on a more copious blood supply: also, as rightly 

 suggested by Maffucci, on the fact that this organ, after splenectomy 

 for malarial hypertrophy, becomes the principal repository for 

 parasites and malarial pigments. 



It has been maintained that the spleen, after total extirpation, 

 is reproduced or regenerated in the form of one or more lesser 



