ATLAS 



OF THE 



FERTILIZATION and KARYOKINESIS 



OF THE OVUM 



By EDMUND B. WILSON, Ph.D., 



Professor of Invertebrate Zoology hi Columbia College 



WITH THE CO-OPERATION OF 



EDWARD LEAMING, M.D., F.R.P.S., 

 Instructor in Photography at the College of Physicians and Surgeons, Columbia College 



WITH TEN PHOTOGRAPHIC PLATES AND NU.MEROUS DIAGRAMS 



Extra 8vo. Cloth, pp. vii + 32. $4.00, net. 



This work comprises forty figures, photographed from nature by Dr. Learning from the 

 preparations of Professor Wilson at an enlargement of one thousand diameters, and 

 mechanically reproduced by the gelatine process, without retouching, by Edward Bierstadt 

 of New York. The plates are accompanied by an explanatory text, giving a general intro- 

 duction to the subject for the use of students and general readers, a detailed description 

 of the photographs, and over sixty text-figures from camera-drawings. 



It is the object of this atlas to place before students and teachers of biology a practically 

 continuous series of figures photographed directly from nature, to illustrate the principal 

 phenomena in the fertilization and eariy development of the animal egg. The new science 

 of cytology has in the course of the past two decades brought forward discoveries relating 

 to the fertilization of the egg and the closely related subject of cell-division (karyokinesis) 

 that have called forth on the part of Weismnnn and others some of the most important 

 and suggestive discussions of the post-Darwinian biology. These discoveries must in 

 some measure be dealt with by every modern text-book of morphology or physiology, yet 

 they belong to a region of observation inaccessible to the general reader or student, since 

 it can only be approached by means of a refined histological technique applied to special 

 objects not ordinarily available for practical study or demonstration. A knowledge of the 

 subject must therefore, in most cases, be acquired from text-books in which drawings are 

 made to take the place of the real object. But no drawing, however excellent, can convey 

 an accurate mental picture of the real object. It is extremely difficult for even the most 

 skilful draughtsman to represent in a drawing the exact appearance of protoplasm and the 

 delicate and complicated apparatus of the cell. It is impossible adequately to reproduce 

 the drawing in a black-and-white text-book figure. Ever>' such figure must necessarily be in 

 some measure schematic and embodies a considerable subjective element of interpretation. 



The photograph, whatever be its shortcomings (and no photograph can do full justice 

 to nature), at least gives an absolutely faithful representation of what appears under the 

 microscope ; it contains no subjective element save that involved in the focussing of the 

 instrument, and hence conveys a true mental picture. It is hoped, therefore, that the pres- 

 ent work may serve a useful purpose, especially by enabling teachers of biology to place 



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