292 The Microscope. 



If care is taken, specimens on a slide with a cover can be 

 secured in water, by a dextrous use of gold size or varnish, using 

 a soft brush and the turn table. 



To cultivate these nematodes, express and filter the juice of 

 the food-plant in which they are found, to a drop of this in a 

 concave centred glass slide, or a " life cell," place a mature 

 gravid worm, cover with thin glass, examine dail}'^ the changes 

 that take place, and every three or four days supply fresh fluid, 

 and you can see all the varied changes, the rapid segmentation 

 of the egg — figure 2 — the differentiation of the male and female 

 — figures 4 and 5 — the castings of the skin, and the magic 

 breaking, and the final change in the egg from a closed tube to 

 a rapidly moving worai. 



There are many things yet for our microscopists to discover. 

 How these nematodes penetrate tissues, how they copulate, why 

 the " gall " is formed, the effect of various poisons available as 

 protective remedies, the amount of heat and cold they can en- 

 dure, and a complete list of plants they do not attack, especially 

 of trees and plants valuable as " stocks " for grafting or bud- 

 ding, or that can be used in " starving ©ut " infected fields. 



These worms, as Dr. Cobb well says, are near the limit of 

 microscopic study and will tax one's gift of continuance severely, 

 but I know of nothing that offers such a remunerative field. 



CYTOLOGY OR CELLULAR BIOLOGY. 



X. — CYTODIERESIS OR CELL-DIVISION. 

 REV. A. M. KIRSCH, C. S. C. 



rpHUS far we have studied the cell in its static condition, but 

 -L in this concluding article it is my intention to give the 

 reader some idea of the cell in its dynamic state. We have seen 

 the remarkable structure of the nucleus and protoplasm when in 

 the state of rest, but during the activity, resulting in cell divi- 

 sion, these structures undergo radical and fundamental changes. 

 Before entering upon the study of this diflTicult subject, it is 

 necessary for us to fix the meaning of the terms used ; and let 

 me state at once that with certain authors the creation of new 

 technical terms seems to be the main object. Why should 

 science be burdened with a number of unnecessary terms ? 



