matin particles. Dr. Williams also showed that reproduction by division and by budding takes place, and she failed only to make out the conjugation processes. From my own study of Dr. Williams's preparations, I have no doubt at all that she is right about the organism, and believe that, under her name Neurorcytes, it should be grouped with the rhizopod-like protozoa.
This work on Neurorcytes is also very interesting from the side light it throws on the small-pox problem. Here again, in certain phases of variola, we find curious intra-cellular and intra-nuclear bodies having a striking resemblance to the ordinary unstained forms of the Negri bodies. These small-pox bodies were early recognized as characteristic of this disease, and Guarnieri in 1892, believing they were protozoa of a specific kind, named the organism Cytorcytes variolæ. Perhaps the majority of pathologists to-day and many biologists, are opposed to this interpretation,' and these bodies, like the Negri bodies, are more commonly regarded as specific secretions or degenerations than as protozoa. I have no doubt myself, from long study of these small-pox organisms, that they are protozoa, and believe that with fresh material and by using the stain which Dr. Williams has so successfully used for Neurorcytes, the last doubter will be convinced.
At the risk of going somewhat far afield in pathological speculation, let me briefly call attention to one other possibility of amœboid organisms and disease, viz., cancer. For years it has been known that vegetable cells in ordinary edible forms, like the cabbage or turnip, etc., may be stimulated to abnormal multiplication by rhizopod parasites. Such a parasite—Plasmodiophora brassicæ—enters the young root cells of a cabbage, stimulates those cells to an unwonted degree of multiplication until great tumors are formed giving rise to the vegetable disease known as 'club-root.' The plant cells become storage reservoirs of the spores of Plasmodiophora, and when the plant dies down the spores are liberated in the soil. Now it has been argued that if vegetable cells can be stimulated to abnormal activity, there is no real biological objection to animal cells being similarly stimulated to division by animal parasites, and some pathologists have gone so far even as to see in certain cell inclusions of cancer peculiar bodies which they compared with the Plasmodiophora spores. The comparison, however, can not be sustained, and without going into the subject extensively I may say in short that nothing has ever been seen in cancer cells that can be interpreted as a protozoon parasite. This, however, does not weigh against the parasite theory of cancer—a theory which I personally, believe to be the only one that satisfactorily explains the disease. The organism of yellow fever has never been seen, but no one doubts the parasitic nature of that disease and the fact that the virus or the germs of yellow fever pass through the finest Berkefeldt
