NATORE 
261 
THURSDAY, JULY 22, 1886 
HAND-BOOK OF PLANT DISSECTION 
fland-Book of Plant Dissection. By J. C. Arthur, M.Sc., 
Charles R. Barnes, M.A., and John M. Coulter, Ph.D. 
(New York: Henry Holt and Co., 1886.) 
HIS work will take the same place in the botanical 
teaching of the United States as will be occupied 
in this country by the “ Practical Botany” of Messrs. 
“Bower and Vines, when the latter is completed. Both 
are essentially guides to the laboratory instruction which 
now forms the most important part of every efficient 
course of botany. 
The American hand-book differs from its English proto- 
type in two important respects : first, in the fact that it 
begins with the lowest plants, while the English work 
begins with the highest ; and secondly, in its more rigid 
adherence to the type system. Prof. Bower did not limit 
the work entirely to the main types, but frequently intro- 
duced other plants, which happened to be more favour- 
able for the study of particular points of structure. The 
authors of “ Plant Dissection,” on the other hand, give us 
the type, and the type only. Their plan has the advantage 
of simplicity, but several points have to be passed lightly 
over which could have been studied efficiently in plants 
other than the selected types. - On the whole, the more 
elastic method of the “ Practical Botany” seems to us to 
be more satisfactory. Any teacher of botany would 
select Cucurbita for the study of the sieve-tubes, Caltha, 
or some allied plant, for the embryo-sac, and so on; and 
yet these are not plants which would be well suited for 
generally typical examples. 
As regards the other point, whether it is better to begin 
at the upper or lower end of the vegetable kingdom, it 
may perhaps be said that the former is the course better 
adapted for beginners, while the latter has its advantages 
in the case of advanced students. If the learner has no 
previous knowledge of plants at all, it may be difficult to 
rouse his interest in such obscure forms as Oscillaria or 
Cystopus, while the study of some familiar plant, such as 
the sunflower or shepherd’s purse, is much more likely to 
attract him. On the other hand, if some preliminary 
knowledge may be assumed, there will be no objection to 
following the strictly logical course of proceeding from 
the simpler to the more complex. 
The “ Hand-Book of Plant Dissection” begins with a 
short introduction on reagents, section-cutting, &c., and 
then come the types, occupying the bulk of the work. 
They are twelve in number, and have been selected as 
follows: —For the lower Chlorophyceze, Protococcus 
viridis ; for the Cyanophycee, Oscillaria tenuis ; for the 
Conjugate, Spzrogyra guinina; for the Phycomycetes, 
Cystopus candidus ; for the Ascomycetes, MWicrosphera 
Friessi ; for the Liverworts, Marchantia polymorpha ; for 
the Mosses, Atrichum undulatum ; for the Ferns, Adian- 
tum pedatum ; for the Gymnosperms, Pinus sylvestris ; 
for the Monocotyledons, Avena sativa and Trillium 
recurvatum ; and lastly, for the Dicotyledons, Capsella 
Bursa-pastoris. It willbe seen that while one or two of 
these plants are strictly American forms, most of the 
types are cosmopolitan. 
VOL. XXXIV.—No. 873 
It would be easy to criticise the selection in some of 
the cases: thus, “ Protococcus” is not really entitled to 
the first place on the list, for its cells are more highly 
organised than those of the Oscillaria. Pythium shows 
the sexual organs much better than Cystopus, and Micro- 
sphzra is perhaps not so characteristic an Ascomycete as 
might have been found. On the whole, however, the 
types are good ones. 
A few points may be mentioned where there appears to 
us to be room for serious criticism. It is evident from 
the remarks on p. 55 that Sachs’s old classification of the 
Thallophytes is adhered to. Surely after the publication 
of De Bary’s papers in the Botanische Zeitung, in 1881, 
and of Goebel’s “ Grundziige der Systematik,” in 1882, 
there is no excuse for retaining this manifestly artificial 
arrangement. Sachs’s grouping of the Thallophytes by 
their sexual organs alone, without any regard to general 
structure, has been unkindly, but pointedly, compared to 
the sexual system of Linnzus, which is not usually 
reckoned as a natural arrangement. How inexpedient 
the classification in question is for the student is well 
shown in the work before us on the page referred to, 
where the reader is advised to study Nemalion or Batracho- 
spermum in order to understand the fruit of Micro- 
sphzera. Can any one seriously believe that detailed 
homologies can be traced between so isolated a group as 
the red seaweeds and a highly specialised parasitic mem- 
ber of the Ascomycetous Fungi ? 
Going on to the chapter on the Liverwort, the foot- 
note on p. 75 seems likely to confuse rather than to 
enlighten the student. The archegonia are of called 
sporogonia after fertilisation by any one who wishes to 
keep the distinction between the sexual and asexual 
generations clear in the mind of the learner. The sporo- 
gonium arises from the oosphere only ; the archegonium, 
as distinguished from the oosphere, takes no part in its 
formation. 
In the same chapter a statement on p. 82 that ‘‘the 
antheridia are modified hairs” demands notice. This is 
a bad example of old-fashioned morphology. The 
antheridia of the Liverworts are modified successors of 
the antheridia of the lower plants. The ancestors of 
highly organised plants like Marchantia must have long 
possessed sexual organs, probably at least as long as 
they have possessed “trichomes.” The same mistake 
reappears on p. 120 in the description of the fern, when 
the “trichomes” are said to appear “in the form of 
sporangia.” Either this is merely a roundabout way of 
stating that the sporangia are of epidermal origin, or 
else it means that these reproductive organs are actually 
due to the modification of hairs. The latter view will 
hardly commend itself to any one who realises that the 
spores of the fern are homologous with those of the 
Muscinez. 
A repetition of the same confusion of ideas on p. 125 
need not be further noticed. 
In the account of the anatomy of the leaf of Pinus 
there is an error as to a simple matter of fact which 
ought to be corrected. On p. 154, @ and e, the thin- 
walled cells of the mesophyll, are said to be empty, while 
those with bordered pits are described as having “more 
or less conspicuous contents.” This is just the reverse of 
the truth. The thin-walled cells have protoplasmic con- 
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