XVlll 
INTRODUCTION. 
The colour ascertained, he now knows in which of the three colour-groups to look for his 
plant, and may proceed next to consider to which of the principal divisions of its group it 
belongs ; whether to the flats, the cylindricals {i.e. those shaped like a thread, whether coarse 
or slender), the incrustations, or irregular lumps. Then — if flat, for instance — he must 
go on to observe whether it is with or without a midrib ; whether leaf-lilce or irregular in shape ; 
whether branched or unbranched^ &c. ; for it is impossible to do more here than give a general 
idea of how the investigations are to be pursued. They will need patient labour and careful 
observation ; but if these are given they will probably be successful. What the Synopsis fails 
to give, the specific descriptions and plates will probably supply; and the List of Families, 
Genera, and Species, which follows, will enable the student to reduce his scattered materials 
into their proper order, and arrange his plants in the herbarium according to their scientific 
classification. 
It is true the difficulties increase as the inquiry proceeds. It is easier to find the 
generic than the specific name of a plant ; to trace it home to its family, than to identify it as 
an individual. But those who have accomplished the one are little likely to rest satisfied 
without attempting the other. And if a real difficulty occurs, surely some more advanced 
naturalist-friend can always be got hold of to throw light on the subject. For brotherhood is 
strong among them — especially among the highest — whose readiness to help the ignorant, 
even at the expense of much valuable time and trouble, is an example which all will do well to 
imitate. On the other hand, the “ ignoranF should carefully guard from presuming on such 
good nature. A habit of recklessly sending unexamined specimens to be named — a dozen 
of one sort perhaps — cannot be too strongly deprecated. But a real difficulty, which the 
possessor of a plant has tried in vain to surmount, is sure to be kindly and considerately 
met by any one to whom reference is made. 
Very little more remains to be said, except on the subject of microscopic examination. In 
the course of these descriptions, especially in the latter ones, certain characters of plants, or the 
plants themselves, are described as microscopic objects. And it was necessary to state this, in 
describing such species as are only distinguishable from each other when observed through 
a power of the microscope high enough to reveal internal structure (see Plates LXXVIII. 
LXXIX. and LXXX.). A microscope, therefore, is one of those desirable possessions which 
almost amounts to a necessity, and is absolutely such to a student who intends to investigate 
thoroughly for himself. The internal tubes of a Polysiphonia, for instance (Plate XXV., &c.), 
cannot be seen without it, any more than the differences among Lyngbyas, Microcoleus, 
Oscillatorias, Monormia, &c. (Plate LXXVIII., &c.). And in days when an actually useful 
instrument may be had for 10s. 6c?., and very good ones for a few pounds, it is to be hoped 
that few will be unable to afford themselves the luxury of such an assistant. For a luxury 
that is, indeed, which will so often resolve perplexing doubts by a glance, and save many weary 
hours of uncertain labour. 
Connected with the microscope is, of course, the subject of examining plants by making 
sections of them. The Germans call a section a durchschnitt, or through-cut- — expressively 
enough ; and this durchschnitting is a necessary accomplishment to an advanced, i.e. a scientific 
student. Some genera even are wonderfully alike, till a durchschnitt reveals a difi'erence in 
internal structure ; when, behold, plants which might be taken for twin brothers have to be 
separated as wide as the poles, and the fructification of algae can never be understood without 
