Aug. 11, 1870| 
NATURE 
293 
once been perplexed by finding that the specimens which 
have been provided for illustration belong to a species 
differing in some point of structure from the characters 
which he has given as belonging to the order under 
consideration. Teachers will also differ as to the relative 
importance of certain points of structure, and conse- 
quently as to the position of some Natural orders. The 
uncertainty which still hangs over our classification will 
be illustrated by the following list of points in which the 
book before us differs from the fourth edition of Professor 
Babington’s “ Manual of British Botany,” published as 
recently as 1856: Droseracee has been moved from Tha- 
lamifloree to Calyciflorae, the genus Parnassta being 
incorporated with Saxifragee,; Acerinee undergoes the 
same change of position; Balsaminee and Oxalidee 
are abrogated as separate orders, their genera being 
united to Geraniacee,; Portulacee, Tamariscinee, and 
Paronychtee, on the other hand, are transferred from 
Calycifloree to Thalamiflorae, the tribe Sfergulee, how- 
ever, of the latter order being relegated to Caryo- 
piyllee ; Grossulariacee is no longer found as a separate 
order, but is united to Saxifragee ; [licinee or Aqut- 
Joliacee changes its quarters from Corolliflore to Thala- 
mifloree ; Lovanthacee from Monopetalze to Apetala ; 
Empetracee from Apetale to Thalamiflore ; while the 
apetalous order of Callitrichacee disappears, its species 
being found under Calycifloree united to Haloragee ; the 
hop, on the other hand, is eliminated from Urticacce, 
and appears as a separate order, Cannadbinee, and 
Babington’s miscellaneous collection of Amentifer@ is 
divided into the four distinct orders, Sadicinew, Cupulifera, 
Betulacee, and Myricacee,; Trilliacee, Colchicacee, and 
Asparagee are combined with Zzdiacee. Although these 
alterations concern chiefly comparatively small and unim- 
portant orders, there is sufficient change to perplex the 
student, independently of minor re-arrangements of genera, 
&c. On the whole it will be seen that the tendency is 
towards the English practice of “lumping,” as contrasted 
with the Continental practice of “splitting,” the number 
of orders of Flowering Plants being reduced from ninety- 
seven to ninety-two. We are glad, however, to find that 
this tendency is not carried to the extent we meet with 
it in Hooker and Bentham’s “ Genera Plantarum,” where 
Papaveracee and Fumariacee are united; we doubt, 
indeed, whether the interests of students would not have 
been better served by keeping apart orders with such clear 
distinctions of outward structure, as far as British species 
are concerned, as Saxifragee and Grossulariacee; Gera- 
niacee, Oxalidee, and Balsaminee » Liliacee and Colchi- 
cacee. The re-arrangements of position are no doubt, 
in nearly all cases, based on correct botanical principles. 
The difficulty, however, often experienced in drawing up 
satisfactory diagnoses of the natural orders may be illus- 
trated by comparing those given by such authorities as 
Hooker and Oliver. In Hookers ‘“Student’s British 
Flora,” for instance, we find the pistil of Vymphaacee 
described as “syncarpous ;” in Oliver’s “ Lessons on Ele- 
mentary Botany,” as “apocarpous.” Hooker speaks of 
the stamens of O/einec as “ epipetalous,” Oliver as “hypo- 
gynous.” Inthe synopsis of natural orders given at p. xiv. 
of the book under review, mention of the hypogynous 
stamens in some genera of O/ezze@ is omitted. 
Inhis analysis of certain difficult and intricate genera, 
Dr. Hooker has followed the lead of botanists who have 
made them their special study, as in the case of Rubus, 
Rosa,and Hieracium, where Mr. J. G. Baker’s descriptions 
are adopted. This, no doubt, was a wise course in these 
instances ; we regret, however, to find in the whole work 
so little of the author’s own observations ; we are sure 
that in many cases he could have improved greatly on the 
method of the “ London Catalogue,” which has been too 
implicitly followed. This is especially the case with re- 
gard tothe plants admitted as “ colonists” or “ denizens.” 
Why should a place be given, for instance, to Galinsoga 
parviflora, found nowhere, we believe, except within a 
radius of a few miles from Kew Gardens, from which it 
has escaped? while, on the ballast hills of the north-east 
coast and some other localities, many plants have 
apparently become permanently established, of which no 
mention is made, or their name is merely given in the 
Appendix. The time of flowering of plants is also one 
on which little exact observation appears to have been 
made ; one would judge from our hand-books that the 
only wild flowers to be gathered in December and 
January are the groundsel and the daisy; while at least 
a dozen others could be named that are equally, if not 
more, perennial. We shall look with eagerness for a work 
embodying a record of recent physiological and morpho- 
logical observations on British plants, which Dr. Hooker 
states, in his preface, it was his original intention to have 
incorporated with the present volume, and which will 
possess so great a value from his pen. 
The specific descriptions in Dr. Hooker’s “ Student’s 
Flora” are so admirable, terse, and yet sufficient, the 
arrangement so excellent, and the size so convenient, 
that it must rapidly become the work in general use, the 
companion of every botanist during his summer rambles, 
ALFRED W. BENNETT 
WATER ANALYSIS 
Water Analysts: a Practical Treatise on the Examination 
of Potable Water. By J. Alfred Wanklyn, M.R.C.S., and 
E, T. Chapman. Second Edition, edited by E. T. Chap- 
man, Member of the Council of the Chemical Society. 
Pp. 108. (London, 1870.) 
] N the preface to this edition we are told that the whole 
of the last edition has been transferred almost 
without alteration, but with slightly different arrange- 
ment ; and that some new matter has been added, con- 
sisting of the tetration of waters ; a modification of the 
process for estimating nitrates; a chapter on volatile 
organic matter ; a method of estimating minute traces of 
lead; and a chapter on the purification of waters. The 
tetration of waters is the estimation by standard solutions 
of the amount of acid present in waters contaminated by 
the refuse of certain factories or in rain water which has 
fallen near alkali works. We had thought that the word 
tetration, in the preface, was a misprint for 7étration 
until we found it so spelt in the text ; the latter word (or 
modification), however, appears on p. 38. The modifi- 
cation of the process for the estimation of nitrates consists 
in treating the water to which caustic soda has been added 
with a large excess of aluminium scraps, and pouring off 
