202 PREPABATION AND MOUNTING 



simultaneously open, and in a few hours afterwards the 

 surface of the larger prothallia will be found almost covered 

 with moving antherozoids. Such prothallia as exhibit 

 freshly-opened archegonia are now to be held by one lobe 

 between the forefinger and thumb of the left hand, so that 

 the upper surface of the prothallium lies upon the thumb ; 

 and the thinnest possible sections are then to be made with 

 a narrow-bladed knife perpendicularly to the surface of the 

 prothallium. Of these sections, which after much practice 

 may be made no more than l-15th of a line in thickness, 

 some will probably lay open the canals of the archegonia, 

 and within these, when examined with a power of 200 or 

 300 diameters, antherozoids may be occasionally distin- 

 guished." 



Another interesting object to the young microscopist is 

 afforded by the spores of the Equiseta (or Horsetails, as 

 they are often called). These may be obtained by shaking 

 the higher portion of the stems when the spores are ripe. 

 They will then fall like small dust, and may be placed 

 under the microscope. The spores are then seen to consist 

 of a somewhat heart-shaped mass with bands rather in- 

 tricately curled around it. As they dry, these bands 

 expand, and are seen to be four lines at right angles, with 

 the ends clubbed, as it may be called. If, whilst watching 

 them, the spores are breathed upon, these bands immediately 

 return to their former state, and are closely curled around 

 the spore ; but as they gradually dry, again expand. This 

 experiment may be repeated many times, and is a very 

 interesting one. 



The preceding are the principal objects which could not 

 possibly be included in any of the former chapters, but 

 would have left a most interesting branch untouched had it 

 been neglected. There is another subject also which should 

 not be passed by , viz., the production of minute pictures 

 which serve as objects for microscopic examination. I 

 may here mention that as this manual is simply to 

 enable the student to prepare and mount his objects, the 



