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THE POPULAR SCIENCE MONTHLY. 



Fig. 1. Yeast-Cells. 



the study of the cells of growing plants. It becomes, then, a matter of 

 some interest to know something about these cells ; and, if the reader 

 can imagine himself for a little while looking through the lenses of 

 our microscope, it will be the purpose of this article to tell him some 

 little of what he may see while he studies the cells of plants. 



We may begin with the simplest form of plant-cells ; and so, for 

 our first experiment, let us examine a drop of brewer's yeast. Here 

 (Fig. 1) are the cells of the famous yeast-plant, the cells which are the 

 active agents wherever yeast is employed, whether in the beer-vat or 



batter-crock. In both cases we find the 

 cells producing fermentation : desirable 

 in beer for the sake of the alcohol re- 

 sulting ; in bread, for the carbonic gas 

 set free in form of bubbles, which, per- 

 meating the dough, make it spongy and 

 light. But look at the shape of these 

 cells. Little oval bodies they are, some 

 almost round. Many are entirely iso- 

 lated, so that we see a single cell may 

 constitute the entire plant ; some are 

 linked together, as links in a chain. 

 The attachment here, however, is not 

 very intimate, when once the cells have attained their full size, for 

 then each cell readily and naturally parts company with its neigh- 

 bor parent, I should rather say, for the cells, as they adhere together, 

 represent really so many successive generations, and illustrate for us 

 one method of cell -multiplication, namely, that which is effected 

 by budding. New cells are continually pushed out as buds on the 

 sides of cells already in existence. The buds grow, reach maturity 

 very rapidly, and in a very short time themselves give rise to new 

 buds and cells. These little yeast-cells, which are not more than three 

 or four ten-thousandths of an inch in diameter at most, are about as 

 simple vegetable cells as we may find anywhere. Growing thus iso- 

 lated from each other, hardly so much as jostling one another in life's 

 race, there seems no reason why such cells should not be perfectly 

 spherical, or why, so to speak, life's work should not, with them, result 

 in a well-rounded whole. 



But the yeast-plant belongs low down in the scale of life, and its 

 simplicity of cell-structure corresponds well with its rank. For the 

 greatest variety of form among plant-cells we must look to higher 

 plants, though not to the highest. The Algce, in their marine forms 

 well known to every gatherer of " sea-moss," and in fresh-water forms 

 familiar to ail microscopists, afford cells of almost every imaginable 

 shape, character, and color. Here, as with the yeast-plant, a single 

 cell ofttimes makes up the entire organism, but, while some cells are 

 simple, others branch and divide in all directions : some simulate the 



