DECrjiBER 23, 1904.] 



SCIENCE. 



879 



filtration theory of Claude Bernard, involves 

 not only filtration, but osmosis and diliusion. 

 The arguments for the secretion theory are 

 more fully given, but not well analyzed. For 

 example, Eauvier's observation that the large 

 sacs, which are so characteristic of developing 

 lymphatic capillaries, are filled with a fluid 

 different from blood plasma is given as evi- 

 dence that this fluid is the result of secretion, 

 while as a matter of fact it is not an argument 

 for one side more than the other. 



The subject of the leucocytes is a diificult 

 one to treat. The descriptions of the dif- 

 ferent tj73es are excellent, much better than 

 ■in the average text-book, and can not fail to 

 be helpful to the student. Many special 

 points, familiar to one with experience in 

 blood work, but perplexing to the student, are 

 brought out. For example, the difficulty of 

 drawing a sharp line between the small and 

 large mononuclears. The different solubilities 

 of the granulations is another valuable point. 

 The theory of phagocytosis is so identified 

 with the name of Metchnikoff that one is 

 surprised to find but a casual mention of his 

 work in this connection. It also seems a mis- 

 take not to mention that in view of the 

 studies on chemiotaxis and immunity our 

 ideas of the physiology of the leucocytes now 

 include much more than phagocytosis. 



In regard to the granulations, our author 

 asks of what is the physiological value of dis- 

 tinctions established by color reactions. This 

 point is brought out in a more interesting 

 and fruitful way by Ehrlich in his book on 

 ' Die Anaemie,' when he says that only a part 

 and, perhaps, only a small part, of our knowl- 

 edge of leucocytes can come from histological 

 studies, that we must turn to experimental 

 work and to pathology for a wider knowledge. 

 However, the classification given by our au- 

 thor is based on the granulations and we be- 

 lieve that it is the best classification that we 

 have. No classification can be thoroughly 

 rational until we know the origin of the leuco- 

 cytes. The grouping given by Delamere is 

 certainly practical. He divides the leucocytes 

 into five classes: (1) microcytes (lympho- 

 cytes). (2) macrocytes (large mononiiclears), 

 (3) cells with neutrophilic granules (poly- 



morphonuclears), (4) cells with acidophile 

 granules (eosinophiles), (5) cells with meta- 

 chromatic basophile granules (mastzellen). 

 This is based as much as possible on the 

 granulations, for the macrocyte has basophile 

 granules and the microcyte is without gran- 

 ules. This classification is also best adapted 

 to the study of bone marrow. 



In regard to the theories of the formation 

 of the leucocytes the treatment is again weak. 

 The theory that the leucocytes come fro.n 

 the lymph nodes, and the granular forms from 

 the bone marrow, is attributed to Denys. This 

 theory our author brushes aside on the ground 

 that the leiicocytes are jsresent before the 

 bone marrow is formed. This is of course 

 true, just as much as that lymphocytes occur 

 in the thymus before lymph nodes are formed, 

 and that blood cells occur in the blood islands 

 of the area vasculosa entirely outside the body. 

 This theory, as developed by the Ehrlich 

 school, recognizes that there are many places 

 for the development of blood cells in the 

 embryo, but that in the adult the bone marrow 

 gives rise to the granular forms. It can not 

 be considered as proved, but it gives the most 

 fruitful working bases we have at present. 

 It has been built up through a study of the 

 ansemias and leukaemias and it certainly can 

 not be brushed aside without taking into con- 

 sideration the pathological evidence. It leaves 

 the question of the origin of blood cells from 

 connective tissue open, stating that whether 

 the leucocytes come from preexisting blood 

 cells or from connective tissue cells they are 

 formed in the adult in the lymph nodes and 

 bone marrow. In regard to the origin of the 

 leucocytes from connective tissue our author 

 is dogmatic when he says that it is proved that 

 a leucocyte can become a connective tissue 

 cell, and it is at least very probable that a 

 connective tissue cell can become a white cell. 

 In reality we are waiting for a new way of 

 attacking this problem. 



The chapter on the lymphatic vessels is 

 thoroughly interesting and much in advance 

 of the usual text-book, since it is based on the 

 worjc of Ranvier. It has, however, certain 

 mistakes of Ranvier's. It is as clear a state- 

 ment of the subject as could be given without 



