The summer laboratories and the scientific expeditions which are employing the vacation period of the men of science in this country would make a long list. A vacation from teaching means to the scientific man a chance to work, and at present there are numerous organized means of enabling him to profit by this chance. The most definite form which such arrangements for summer work have taken is the summer laboratory or experiment station for biologists. Such a station affords conveniently the mechanical appliances for scientific work in a good locality for collecting material to work with. The marine or other forms of life are thus made accessible to those whose professional work during the year keeps them in an unfavorable locality. Besides the laboratory at Woods Holl, which is the nearest American representative of Professor Dohrn's great laboratory at Naples, there is an important summer station at Cold Spring Harbor, Long Island, under the auspices of the Brooklyn Institute, and others cared for by Leland Stanford, Jr. University, the University of Indiana, the Ohio State University and other institutions. It is common to combine teaching with research at these laboratories and in some cases they become essentially summer schools, though generally giving courses of a higher order than the ordinary summer school for nature study. But research is often the chief and sometimes the sole purpose of these stations, and a vast amount of work is done each year. The most important of these summer stations is the Woods Holl Marine Biological Laboratory, situated on the southern coast of Massachusetts, between Buzzard's Bay and Vineyard Sound. This laboratory has been fortunate in having been the summer home at one time or another of a majority of the leading zoölogists of the country. It has been usual for the advanced students in universities to take courses or carry on research there, and Woods Holl training has been a valuable recommendation. The reason is not far to seek. The material advantages, the spirit of zeal for concrete fact, the acquaintance with superior men in the science and with a large number of equals, all help to give the best sort of professional training. Such a place also serves as a refinery where opinions and theories may be purified by healthy criticism and by the subtler influence of example. There is a story of three eminent biologists who got involved in a controversy over a disputed question. They argued for a while. Finally one of them said: "Let us get the eggs in question and study them together." This was done, and the three men spent the afternoon over their microscopes patiently working out the problem together; and they did work it out. One of the great advantages of summer laboratories is that they put fellow-students in a frame of mind in which they can work things out together.
The Woods Holl Laboratory has a right to claim a large share in the credit for three of the most important developments in biology in the last decade—the study of 'cell lineage,' of regeneration of organs and of the influence of abnormal conditions on the development of embryos. Workers there have traced the development of the different cells into which the egg-cell divides and have discovered just what parts of the body arise from each group of cells. They have shown that the way in which the egg divides and redivides is as constant, is as much a part of the nature of the animal, as its adult form and structure are. They have replaced pre-