April 26, 1883 | 
L. Math. Soc. Proc.—t1866 (a) A Problem in Probabili- 
ties connected with Parliamentary Elections ; 1868 (4) 
Equilibrium of Forces in Space; 1871 (c) Question in 
the Mathematical Theory of Vibrating Strings ; 1872 (d) 
On some recent Generalisations in Algebra (Presidential 
Address) ; 1874 (e) On the Contact of Quadrics with 
other Surfaces ; 1876 (f/f) On Determinants of Alternate 
Numbers; (g) On Curves having Four-point Contact 
with a Triply-infinite Pencil of Curves ; 1879 (#) On the 
Twenty-one Coordinates of a Conic in Space; (7) On 
Clifford’s Graphs ; 1881 (7) On the Polar Planes of Four 
Quadrics; 1882 (4) On Quartic Curves in Space. 
“A MANUAL OF THE INFUSORIA” 
A Manual of the Infusoria,; Including a Description of 
all known Flagellate, Ciliate, and Tentaculiferous Pro- 
tozoa. By W. Saville Kent, F.L.S., F.Z.S. (London: 
David Bogue, 1882.) 
HE Philosophical Transactions of the Royal Society 
of London for the year 1677 contain the first pub- 
lished account of the minute organisms to which the term 
“ Tnfusoria’’ is now very generally applied. The account 
is by “Mr. Antony van Leeuwenhoek,” who, taking up 
the line of study so successfully pursued by his com- 
patriot, Swammerdam, was the first to apply the micro- 
scope to the investigation of the otherwise invisible fauna 
and flora which teem in inconceivable abundance in the 
waters of ponds, rivers, and seas, in the infusions of 
organic substances prepared by man’s agency, and in 
even the minutest drops of moisture which accumulate on 
the surfaces of natural objects. 
Henry Baker (1742), O. F. Miller (1773), and other 
names are connected with the history of this field of in- 
vestigation in the period antecedent to Ehrenberg, who 
in 1836 gave a new aspect to the subject by his descrip- 
tions and figures of a great number of forms and of their 
intimate organisation. The minute creatures at one time 
spoken of as “animalculz,” and later as “ Infusoria,” are 
now known to comprise many very diverse series of 
organisms—unicellular plants, variously organised uni- 
cellular animals, as well as animals of multicellular struc- 
ture and high organisation, although of minute size. The 
improvement of the microscope within the last forty years 
and the studies of a host of observers, among whom are 
Dujardin (1841), von Siebold (1845), Stein (1854), 
Clapartde and Lachmann (1858), Max Schultze (1860), 
and more recently of Haeckel, Engelmann, and Biitschli 
—have gradually resulted in the recognition of a 
series of minute animals included amongst the “animal- 
cule” and “Infusoria” of earlier writers, which are 
characterised by having their living substance in the 
form of one single nucleated corpuscle or “cell,” whilst 
nevertheless exhibiting a considerable degree of organi- 
sation, possessing a mouth into which solid particles of 
food are taken, pulsating spaces within the protoplasm 
of the cell, special organs of locomotion, prehension, and 
protection. These are the mouth-bearing Protozoa, dis- 
tinguished as such from the other unicellular animals 
which have not a special orifice for the ingestion of food 
and constitute the mouthless Protozoa. 
It is to these mouth-bearing Protozoa and a few allied 
mouthless forms that Mr. Saville Kent restricts (as is not 
unusual) the old term Infusoria. Among them the most 
numerous and highly organised are the Ciliata ; far less 
NAT ORE 
601 
abundant and varied are the Tentaculifera (Acinetz), 
whilst the Flagellata have, on account of their excessive 
minuteness, not been properly understood (and were for 
the most part altogether unknown) until very recently, 
some important features in their organisation having been 
first made known by the author of the book which forms 
the text of this article. 
Mr. Kent’s “Manual of the Infusoria’’ consists of 
two large volumes and an atlas of fifty-one plates. The 
first volume contains chapters on the history, the organ- 
isation, the affinities, and the classification of the Infu- 
soria. Then the three classes, Flagellata, Ciliata, and 
Tentaculifera, are taken up one by one and systematically 
divided into orders and families, genera and species—a 
diagnosis and usually a figure being given of every species. 
The systematic treatment of the Ciliata and Tentacu- 
lifera occupies the second volume. Altogether Mr. Kent 
describes goo species of Infusoria, arranged in 300 genera 
and 80 families. To go over this ground in any case in- 
volves a vast amount of labour and perseverance. To do 
so in the thorough and conscientious manner which dis- 
tinguishes Mr. Kent’s work requires special capacity. Mr. 
Kent has spared no pains to make his work a trustworthy 
source of information on all points relating to the group 
with which it deals; the most comprehensive as well as 
the smallest and most obscure of recent publications 
relating to the organisation or to particular species of 
Infusoria have their contents duly set forth in the proper 
place in Mr. Kent’s work. So faras a frequent reference 
to these volumes enables one to come to a conclusion, 
little if anything of importance, whether published in 
English, French, German, or Italian, has been overlooked 
by our author. Even the quite recent observations of 
Foettinger on the parasitic Bexedenta found in Cephalo- 
poda, and of Joseph Leidy on the parasitic Ciliata occur- 
ring in the Termites,are incorporated, as well as the 
observations of Cunningham on Protomyxomyces, little 
more than a year old. 
This is by no means the only merit of Mr. Kent’s work, 
He might have contented himself with recasting the 
materials to be found in the three great volumes pub- 
lished by Stein, in Claparéde and Lachmann, and in 
Pritchard’s “‘ Infusoria”’ (a valuable book in its day), and 
have simply incorporated with these the results scattered 
through the various English and foreign journals and 
transactions of the past twenty-five years. Mr. Kent has 
duly done all this, but he has done more, since he has 
himself made a very careful and prolonged study of a 
large number of Infusoria. Accordingly we find through- 
out the present work original observations brought for- 
ward for the first time. These include a number of 
new species and genera, especially among the Flagellate 
and Tentaculiferous forms. The beautiful cup-forming 
monads mounted on branching stalks like a colony of 
Vorticella were first brought prominently into notice by 
that keen observer, the late Prof. James-Clark of Boston, 
and Mr. Kent has followed up the study of these beautiful 
forms in a very thorough manner. On the whole, it may 
be said that the portion of Mr. Kent’s work devoted to 
the Flagellata will have, for those naturalists who have 
not very closely followed the periodical literature of the 
subject, the charm of complete novelty, for very many of 
these forms were completely unknown or misunderstood 
