conditions, nuclear equilibrium is upset, and one element, male or female, becomes predominant, to its own destruction. For, as the process goes on, it enfeebles the progeny, and unless sexual fecundation comes to the rescue as an alternating generation, the organism inevitably perishes. I do not pretend that this is else but the crudest summary of the results of innumerable observations and of a long train of exact mathematical and deductive reasoning; it is cited rather to explain the way in which Schaudinn's attention first became directed to the problems of tropical medicine, and as an example of his generalisations on reproduction, which, begun with the Foraminifera, were ultimately carried step by step through the hsemo-sporidia to the trypanosomes and spirochsetae.
The summer of 1894 Schaudinn spent at the marine biological station at Bergen in Norway, where he published a descriptive list of 139 species of Foraminifera, and on returning to Berlin, at the age of 23, he was appointed chief assistant at the Zoological Institute. Here he worked assiduously for the next four years, augmenting his slender salary by teaching as a privat-docent for the University, and issuing numerous reports containing much new information as to the life-history of Heliozoa, Radiolarians, and Amcfibae. What is regarded by zoologists as one of his best researches, viz., that in which he traced the sexual cycle of the free-living protozoan Trichosphaerium sieboldi through a complete series of alternations, was carried out at this time. During the summer of 1898 Schaudinn, to his great gratification, was sent with his friends, Romer and Friese, an artist, on a scientific expedition to Spitz-bergen. Time is inadequate to follow him to the Arctic zone. It must suffice to say that the trip yielded the keenest enjoyment to the three comrades, and that the scientific results were sufficiently important to justify their publication in book form. Four volumes of this work,
