In these cases, besides the change in number and form of the leukocytes already described, there are frequently found in the blood very minute crystals first described by Charcot. These are small, often adherent to the leukocytes, and most frequently found when eosinophile cells predominate; their exact significance is not known. The pathology of leukemia is too remote from the purpose of this work to receive consideration here. Without asserting its germ character one may say that it is under suspicion, and that various observers have described appearances supposed to indicate a specific cause, probably a protozoön. 2. B. _Pseudoleukemia._--This has, in time past, gone under many different names, of which the most common is _Hodgkin’s disease_ (_q. v._). Many speak of it as _malignant lymphoma_. This is doubtless a disease with a specific cause, as yet unrecognized, which produces very significant changes in the blood, especially in the white corpuscles. The spleen and lymph nodes are both involved, mainly the latter. The general blood changes are quite variable and one may find many types. As a rule, these comprise not so much an increase in the number of leukocytes as a decrease in the number of red cells by which an apparent leukocytosis is brought about; hence the expression _pseudoleukemia_. Many cases, however, will present a certain degree of actual leukocytosis, the proportion of the whites to the reds being about 40 to 50. _What interpretation in general is to be given to leukocytosis?_ A condition deserving this name is, first of all, essentially temporary. In acute infectious diseases it shows itself during the febrile stage and the principal increase is in the finely granular oxyphile cells. In such diseases as erysipelas, as well as pneumonia, it lasts but a short time after the crisis has been reached and the temperature has fallen. In diseases like acute appendicitis and acute peritonitis from any cause a marked leukocytosis may be regarded as indicating the presence of pus; it should be emphasized, however, that _pus may be present without this indication_, and it has been previously stated that such a fact is to be interpreted either as an example of a mild degree of infection or an exceedingly reduced vitality.