1903-1904-] Remarks on Glceocapsa. 133 



" The key to all ultimate biological problems must, in the 

 last analysis, be sought in the cell." " That a cell can carry 

 with it the sum total of the heritage of the species, that it 

 can in the course of a few days or weeks give rise to a mollusc 

 or a man, is the greatest marvel of biological science." — 

 (Edmund B. Wilson.) To those students who devote them- 

 selves to the investigation of human diseases, to the ultimate 

 betterment of our race, the knowledge gained in the investiga- 

 tion of these apparently useless organisms is of the utmost 

 importance. Many important discoveries owe their origin to 

 the study of these minute specks of life in which throbs 

 protoplasm of a kindred nature to that in the cells of our 

 own bodies. 



EXPLANATION OF THE FIGURES. 



All have been drawn at a magnification of 750 diameters by means of 

 Y oil-immersion objective and " B " eyepiece. 

 Scale — y^gjjths of an inch, — 



I \ \ I I [ 



Fig. 1. A single cell of Glceocapsa crepidinum with its integument, 

 before the beginning of the first division. 



ti 2. The cell beginning to divide. 



ir 3. The first division nearly complete. 



ti 4. Completion of the first division. Soon after division the cells 

 assume a globular form, and the integument of the daughter- 

 cells becomes visible. 



II 5. The two daughter-cells beginning to divide. 



II 6. Completion of the division of the two daughter-cells, each cell 

 with its own integument similar to Fig. 4. After this stage 

 is reached the two outer integuments rupture, and the four 

 liberated cells with their own integuments quicklj' assume the 

 form of Fig. 1, and begin the life-cycle over again. 



M 7. A cell that has been in a resting-cyst condition, beginning to 

 divide (wde p. 131). 



