. Lessons in botany. Botany. i58 BOTANY. there are two rows of small circular dots, one row on either side of the pinna. These are called the '' fruit dots,'' or sori (a single one is a sorus). If we examine it with a low power of the microscope, or with a pocket lens, we will see that there is a circular disk which covers more or less completely very minute objects, usually the ends of the latter projecting just beyond the edge if they are mature. This circular disk is what is called the indusium, and it is a special outgrowth of the epidermis of the leaf here for the pro- tection of the spor
. Lessons in botany. Botany. i58 BOTANY. there are two rows of small circular dots, one row on either side of the pinna. These are called the '' fruit dots,'' or sori (a single one is a sorus). If we examine it with a low power of the microscope, or with a pocket lens, we will see that there is a circular disk which covers more or less completely very minute objects, usually the ends of the latter projecting just beyond the edge if they are mature. This circular disk is what is called the indusium, and it is a special outgrowth of the epidermis of the leaf here for the pro- tection of the spore-cases. These minute objects un- derneath are the fruit bodies, which in the case of the ferns and their allies are called sporangia. This in- dusium in the case of the Christmas fern, and also in some others, is attached to the leaf by means of a short slender stalk which is fast- ened to the middle of the under side of this shield. 262. Sporangia.—If we i, section through the leaf at Rhizome with bases_ of leaves, and roots of the one of the fruit dots, Or if Christmas fern. we tease off some of the sporangia so that the stalks are still attached, and examine them with the microscope, we can see the form and structure of these peculiar bodies. Different views of a sporangium are shown in fig. 137. The slender portion is the stalk, and the larger part is the spore-case proper. We should examine the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Atkinson, George Francis, 1854-1918. New York, H. Holt and company
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