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 Le 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." F. A. B. 



Diet and Blood 



NATURAL Hygiene ; or, Healthy Blood the essential condition of Good Health, and how 

 to attain it. By H. Lahmann, M.D. Translated by Dr H. Buttner. 8vo, pp. 

 viii + 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. 



