corkscrew-shaped bacteria” between the teeth of a human being, the theory was set forth that probably many diseases owe their origin to such “little animals.”[75] The same idea, as will be shown farther on, occurred to the distinguished medical practitioner of Verona, Italy,--viz., Fracastoro,--one hundred years earlier (1546). Leeuwenhoek, it should here be stated, possessed a very great advantage over his rivals in the field of minute anatomy, for he was in the habit of using, in his investigations, microscopes which he himself had made, and which magnified from 160 to 270 diameters, whereas those utilized by the others were capable of magnifying, at the maximum, only 143 diameters. While a large part of the work which he performed shows plainly that he was a skilful and careful anatomist and endowed with good mental powers, Leeuwenhoek nevertheless manifested certain mean traits of character. Daremberg says that these “consisted in his disposition to conceal his technical methods from his associates, and in his jealousy of others--as manifested, for example, toward Leibnitz, who had established a similar laboratory for research work in minute anatomy. These traits of character showed that fundamentally he was not a true lover of science, but rather an artisan. And yet, with all these faults, he does not appear to have placed an inordinately high value upon his discoveries or to have been unreasonably sure of the correctness of his conclusions.” The first monograph published by Leeuwenhoek bears the date 1673. It is a study of the minute anatomy of the bee’s sting. He was the first to declare that the blood is the nutritive fluid _par excellence_, and that it is to be found in the entire series of organisms belonging to the animal kingdom. He divided blood into two parts--the red, or the solid portion, and the serum. The corpuscles which float in the serum and give to the whole fluid its red color, are called by him “particles,” in the case of blood from birds, reptiles and fishes, and “globules” in that from quadrupeds. He employed this term “globules” because he believed that these bodies were exactly spherical in shape. According to Daremberg, Leeuwenhoek’s studies cover the entire field of human histology, and his findings are for the most part correct.