272 PROGRESS OF MICROSCOPICAL SCIENCE. 



the spherical cell only gives rise to a single fusiform cell ; and if 

 the nucleus divides after it has acquired its lateral position, the 

 resulting spindle-cell contains two nuclei. But occasionally the 

 division of the nucleus takes place before or soon after the process 

 of vacuolation commences, and in this case one nucleus remains 

 behind within the hyaline area, and is often surrounded by some 

 granular protoplasm. It may here be developed into another cell, 

 thus lying within the first spindle-cell. The repetition of this 

 process by repeated multiplication of the nuclei produced the con- 

 centric nests. This process of vacuolation can only be distinctly 

 seen in the rapidly growing portions of the tumour, and it was only 

 distinct in fresh specimens. The exact nature of the process and of 

 the hyaline contents of the vacuoli is uncertain. It would appear 

 that these contents are composed of some new, delicate material, at 

 first protoplasmic. The process may be regarded as a simple move- 

 ment of the nucleus and granular protoplasm to the periphery of the 

 cell, but the sharp outline of the vacuoli and the tenuity of the peri- 

 phery suggest that there is an active distending force concerned in 

 the process. Vacuolation in most cases terminates the active life of 

 the original cell ; and division of the nucleus only leads to multipli- 

 cation of the cell if it precede or accompany, not if it succeed, the 

 vacuolation process. The paper concluded with a reference to various 

 descriptions and draA\'ings of the process by different writers, who 

 have, however, for the most part misinterpreted its nature. The 

 examples show how various is the part played by the process in tissue 

 changes. The paper was illustrated by a series of well-executed 

 drawings. 



Mr. Knowsley Thornton had recently examined carefully some spe- 

 cimens of peritoneal cancer, and had found numerous vacuolated cells 

 surrounded by rings of protoplasm. He had never seen anything like 

 an intrusion of other cells into the vacuoli ; and concurred with the 

 view maintained by Dr. Gowers as to the endogenous formation of the 

 new cells. In some specimens a round cell presented central vacuola- 

 tion, an excentric nucleus surrounded by granular protoplasm, within 

 which a development of small cells appeared to be taking place. 

 Staining reagents brought clearly into view the darker granular mass 

 bounding the cell, and this mass seemed to be undergoing a process of 

 cleavage. He had not been able to trace, as Dr. Thin had, the cells 

 to their original starting place ; but in the peritoneum he had noticed 

 projections of oval or round masses of granular material from the 

 stomata, surrounded by germinating endothelium. He could not 

 satisfy himself as to the origin of this material. 



Dr. Thin agreed with Dr. Gowers that the process of vacuolation 

 was not a new discovery. He had, however, never heard it so expli- 

 citly stated as on the present occasion. Had Dr. Gowers disintegrated 

 any of the large " nested cells," and did he believe that division of the 

 nucleus was essential to the formation of the second cell? With 

 regard to Mr. Thornton's remarks, he was surprised that the ideas of 

 stomata and lymph-canalicular systems should be so generally adopted. 

 Many able histologists, including Kanvier, had denied the existence of 



