202 PREPARATION 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 1-15th 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 
500 diameters, a may be occcasionally distin- 
guished.” 
Another interesting beet 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 scen 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 
