220 
, PARASITISM AND SYMBIOSIS. 
(A REVIEW.) 
Parasitology, owing to its economic importance, has received very great attention during 
the last 50 years and several good text-books have been devoted to this subject. In almost 
all recently published books, however, stress has been laid chiefly upon the economic side 
of the problem: medical, veterinary, agricultural, etc., but the scope of Parasitology is by 
no means restricted to the problems economically connected with man. We know now that 
there is hardly any group in the animal or vegetable kingdom which does not harbour 
parasites. The latter themselves do not escape this rule and are often parasitised in their 
turn. Moreover, the interrelations between living organisms are not restricted to parasitism 
only; there are, in fact, all shades of transition between parasitism on the one hand, and 
commensalism and symbiosis on the other. These interrelations have never been adequately 
dealt with in text-books of biology or parasitology and all the information concerning them 
is scattered in a great number of papers dealing with various biological or parasitological 
problems. This gap has been recently filled by a small volume issued by Prof. M. Caullery 
[of the “Laboratoire d’Evolution des Etres Organises de la Sorbonne, Paris] under the title 
Le Parasitisme et la Symbiose 1 in which the author has incorporated a series of lectures 
delivered by him on this subject during the academic year 1919-1920. The book deals with 
the most interesting cases of commensalism, parasitism, and symbiosis and with various 
important cases of transition between these three great ethological groups. 
In discussing parasitic adaptation, the author has examined not only the classical cases 
of parasitism found in the text-books, but he has also included many interesting examples 
of other parasitic groups such as Crustacea, Polychaeta and especially Mollusca which show 
a remarkable series of transitions between ecto- and endo-parasitic life. The author sum¬ 
marises also the results of investigations on several helminths, i.e. Schistosoma, Dibothrio- 
cephalus and Ascaris, whose life-histories have been successfully worked out during the last 
few years. 
Special prominence is given to a series of problems of general parasitology: (1) parasitic 
adaptations, (2) the influence of the parasite upon the host, especially parasitic castration, 
(3) reaction of the host (phagocytic reaction and elaboration of antiferments, formation of 
galls, etc.). The last part of the book deals with symbiosis. In the chapters discussing 
symbiosis in plants, the author lays special stress on the very important work of Noel 
Bernard upon the symbiosis existing between the Orchidae and Fungi. In dealing with 
symbiosis in animals, apart from classical examples, attention is given to symbiosis between 
Insects and yeasts and the intracellular symbionts in Cephalopoda. Portier’s views on the 
dualism of a living cell and the relation between the symbionts and mitochondria are 
submitted to a searching criticism. Prof. Caullery concludes that there is complete lack of 
evidence in support of this theory as we know now that mitochondria are characterised by 
a very low resistence while the symbionts cultivated by Portier appear to be highly 
resistant. The author finally refers to recent work on the aseptic breeding of various animals, 
and especially Insects. This short review only faintly indicates the various problems of 
general parasitology dealt with by the author. 
The book will serve as a well of information for teachers who will find in it ample illustra¬ 
tions of all kinds of interrelations between living organisms; it should stimulate original 
research and enable workers in different fields of parasitology to coordinate the results of 
their investigation with those already obtained and generalised in this most interesting 
volume. 
D. KEILIN. 
1 Caullery, M. (1922). Le Parasitisme et la Symbiose. Encyclopedic scientifique. Librairie 
Octave Doin. Editeur Gaston Doin, 8 Place de l’Odeon, Paris. 400 pp. + 51 figs. Small in 8°. 
