428 NATURAL SCIENCE [December 
of concrete individuals, and is the familiar expression for the whole 
of a system,” that is to say, a pure abstraction. To us the most 
fruitful conception appears to be that of ‘memory’; in other words, 
the tendency to repeat the same action or process under similar, or 
almost similar, conditions. What, if any, may be the ultimate physical 
cause that causes a given readjustment of molecules in any one mass 
of protoplasm to be repeated rather than replaced by another adjust- 
ment, we do not know. But if this tendency, not unknown in the 
inorganic world, be admitted for protoplasm, then at least we have a 
phenomenal foundation for theories of specific segregation, individu- 
ality, and heredity. 
Mr Sandeman’s critical artillery is levelled at the three postulates 
of biology :— (1) “that the qualities of the individual are separate 
constituent elements of which the organism is the total sum”; (2) 
that “all the qualities of the organism and all its stages are the mani- 
festation of, and are related to, one another only through an agent or 
system of agents within the known body”; (3) that “everything 
organic exists only by reason of, and is to be explained only in rela- 
tion to, some special external use which it now has, or which a similar 
structure has had in former times.” The demolition, from a philo- 
sophical standpoint, of various biological theories is well worth reading 
by practical naturalists. Mr Earl’s book should also be read by them, 
for it is to be feared that in our modern schools of science hardly 
enough attention is paid to the logic and fundamental conceptions of 
the subject. “The dissection of typical organisms is not necessarily 
an intellectual exercise.” HeAS B: 
DIET AND BLOOD 
NaturaAu Hyciene; or, Healthy Blood the essential condition of Good Health, and how 
to attain it. By H. Lahmann, M.D. Translated by Dr H. Biittner. 8vo, pp. 
vili+254. 5 plates. London: Swan Sonnenschein & Co. 1898. Price 4s. 6d. 
Dr LAHMANN is a vegetarian and an enthusiast; his book has passed 
through many editions in Germany, and has been translated into other 
tongues ; now for the first time it appears in English. The author is 
able to show a considerable amount of scientific reason for the faith 
that is in him, which may be epitomised in three propositions :—(1) 
that ordinary diet is deficient quantitatively and qualitatively in the 
mineral salts required by the human body ; (2) that we consume far 
too much sodium chloride ; and (3) that we take in water to excess. 
The truth of at least the first two of these propositions is incontro- 
vertible, and Dr Lahmann deserves credit for calling attention to 
them. On this basis he builds his doctrine of “dietetic dysaemia,” 
and proceeds to expound a new pathology for most of the ills that 
flesh is heir to—from short sight to difficult labour. In our opinion, 
he falls into the error of pushing his doctrine to unwarrantable ex- 
tremes—the fate of most enthusiasts. No intelligent person can fail 
to admit the force of certain of his contentions, and no sane pathologist 
can repress a smile at others. The book is worth reading, and is likely 
to do much more good than harm. 
