10 
OF THE ALGiE GENERALLY. 
the plants, and turns them yellow or brown; but even 
that is to be preferred to losing them altogether. At 
the same time the collector should not forget to note the 
fact of their having been immersed in alcohol, otherwise, 
if exchanges are made, strange mistakes may arise as 
to the original colour of the specimen. 
As may be supposed, plants which have grown in swiftly 
flowing streams are more liable to decay after they have 
been gathered, than those whose home is the stagnant 
pond or marsh, since the conditions of life in the latter are 
not so much interfered with by their removal ; indeed, they 
will often continue to live and vegetate in a room, provided 
attention be paid to the chemical quality of the water in 
which they are found. 
As this little work is intended for the collector and not 
for the systematist, nothing will here be said with regard 
to the genera into which the Algje have been divided. 
That portion of their history must be sought for in other 
works, though of course in this, as in every other depart- 
ment of Natural History, an intimate knowledge of both 
genera and species is essential to the student. But, for 
convenience sake and to avoid repetitions, we will, in the 
following pages, confine our treatment of the subject to 
certain heads, corresponding in some degree to the natural 
divisions of systematic authors. 
[Having given on a preceding page one or two examples 
of the lovely patterns which distinguish some of the fila- 
mentous Alga3, it will not be amiss to insert here some 
specimens of the families of Diatomaceze and Desmidiacese. 
The figures will assist the young student in discriminating 
the members of these minute, but important, divisions of 
the vegetable kingdom ; they will also help to point out to 
him what wonderful treasures lie within his grasp, ready to 
be seized as soon as his eye and hand are sufficiently 
educated to make them his own. In the accompanying 
Plates (n. hi. iv. v.) the Diatomace^ are represented by 
figures 9 to 14, the Desmidiacese by figs. 15 to 23. — Ed.] 
