166 LABORATORY STUDIES OF CRYPTOGAMS 



the outline ( x 3-5) ; mark the margin at the bottom of the chief notch 

 as the growing point. Indicate by shading in the proper place any 

 thickened portion, and mark this cushion. Show the root hairs, or 

 rhizoida. 



391 (Compound or Simple). Antheridia. Small prothallia should 

 show the antheridia plainly under the simple lens, especially if the 

 (living) material is first treated with aqueous iodine for two or three 

 minutes and then washed. The antheridia are seen as small round, 

 brown bodies. Indicate their position and relative size on the draw- 

 ing already made. With the compound microscope the general 

 structure of these organs can be made out probably without section- 

 ing, and a drawing may be made. 



392 (Compound or Simple). Archegonia. Older prothallia may be 

 required. Treat with iodine, as before. With a low power the pres- 

 ence and distribution of the archegonia (appearing as numerous short 

 columns of cells projecting from the cushion) may be made out. In 

 many of the older and over-ripe archegonia a central cell, embedded 

 in the prothallium at the base of the projecting neck, is seen as an 

 opaque, brownish sphere. Indicate the position and number of the 

 archegonia on the diagram before drawn. 



The details of structure will require higher powers and sections of 

 the prothallium, either provided already mounted, or made under the 

 teacher's directions. 



393 (Simple). 2. Origin of the spore-bearing plant. From the ma- 

 terial provided find out from what part of the prothallium the leafy 

 shoot springs. Is there a root? and if so, does it originate from the 

 tissue of the prothallium or from the new shoot? Answer these ques- 

 tions in a drawing ( x 2-4). 



394 (Simple). 3. The spores. Examine a "fruiting" leaf of the 

 mature plant. Are the " fruit spots " (sori, sing, sorus) on the upper 

 or under side ? Have they a definite location upon the divisions of 

 the leaf? Indicate the facts in an outline sketch. Pick oft* a leaf 

 segment and placing it on the dissecting stage under the lens, with 

 needles carefully raise the covering (indusium) of a sorus. Estimate 

 the number of spore cases (sporangia) found beneath. Have they 

 stalks? If you have no high-power instrument, draw, highly magni- 

 fied, all the details you can discern with the simple microscope. 

 Much can be made out in this way. Draw (1) the sorus covered by 

 the indusium (if present), (2) the group of sporangia uncovered. 



395 (Compound). If high powers are at hand, further examine 

 sporangia and spores, after removing from the leaf with a knife point 

 and mounting in water in the usual way. 



396 (Simple). Selaginella. With hand lens examine the arrange- 

 ment and shapes of the leaves, and draw a short section of the shoot 

 ( x 3-4) to show these points. Do the shoots of Selaginella grow 



