The Introduction of Agar-agar into Bacteriology.

Among fundamental developments in bacteriology the elaboration of solid culture substrates will always hold first place. With the introduction of a method for isolating micro6rganisms and growing them in pure culture, bacteriologists possessed the means for studying what Ferdinand Cohn (1872) called "Die kleinsten lebenden Wesen." Credit for the discovery of the solid medium technique is commonly accorded to Robert Koch, but, as is usual with discoveries of major importance in science, he had his fore-runners. Of course this detracts in no way from the glory of Koch's achievement; his genius lay in his ability to bring order out of chaos. Starting as it were with a box of miscellaneous beads, varying in size and shape, each bead a scientific fact, he found a thread on which the beads could be strung to form a perfect necklace. There are, it seems, two types of workers in Science, the bead collectors and the bead stringers. Which of the two is more important must not be a question for discussion here. It is a fact, however, that bead collectors are more numerous than bead stringers and it is also an historical commonplace that the bead collectors are more obscure, less known to the world, than those geniuses who string necklaces. The historian of science must concern himself with both types of workers and their productions. The contributions of the obscure are sometimes as important as those of investigators in a more favorable position to be il-