1896.] on Ludwig and Modern Physiology. 23 



body in a given period (hour or day) is balanced by an exactly 

 corresponding amount of heat produced or external work done. It is 

 interesting to remember that the work necessary for preparing such a 

 balance sheet (which Mayer had attempted but, from want of suffi- 

 cient data, failed in) was begun thirty years ago in the laboratory of 

 the Royal Institution by the present Foreign Secretary of the 

 Royal Society. But the determinations made by Dr. Frankland 

 related to one side of the balance sheet, that of income. By his 

 researches in 1866 he gave Physiologists for the first time reliable 

 information as to the heat value (i.e. the amount of heat yielded by 

 the combustion) of different constituents of food. It still remained 

 to apply methods of exact measurement to the expenditure side of the 

 account. Helmholtz had estimated this, as regards man, as best he 

 might ; but the technical difficulties of measuring the expenditure 

 of heat of the animal body appeared until lately to be almost 

 insuperable. Now that it has been at last successfully accomplished, 

 we have, the experimental proof that in the process of life there is no 

 production or disappearance of energy. It may be said that it was 

 unnecessary to prove what no scientifically sane man doubted. 

 There are, however, reasons why it is of importance to have 

 objective evidence that food is the sole and adequate source of the 

 energy which we day by day or hour by hour disengage, whether in 

 the form of heat or external work. 



In the opening i)aragraph of this section it was observed that 

 until recently there had been no tendency to revive the vitalistic notion 

 of two generations ago. In introducing the words in italics I 

 referred to the existence at the present time in Germany of a sort of 

 reaction, which under the term " Neovitalismus " has attracted some 

 attention — so much indeed that at the Versammlung Deutscher 

 Natur for seller at Liibeck last September, it was the subject of one of 

 the general addresses. The author of this address (Prof. Rindfleisch) 

 was, I believe, the inventor of the word, but the origin of the 

 movement is usually traced to a work on Physiological Chemistry 

 which an excellent translation by the late Dr. Wooldridge has made 

 familiar to English students. The author of this work owes it to 

 the language he employs in the introduction on " Mechanism and 

 Vitalism," if his position has been misunderstood, for in that 

 introduction he distinctly ranges himself on the vitalistic side. As, 

 however, his vitalism is of such a kind as not to influence his method 

 of dealing with actual problems, it is only in so far of consequence 

 as it may affect the reader. For my own part I feel grateful to 

 Professor Bunge for having produced an interesting and readable 

 book on a dry subject, even though that interest may be 23artly due 

 to the introduction into the discussion, of a question wliich, as he 

 presents it, is more speculative than scientific. 



As regards other physiological writers to whom vitalistic tenden- 

 cies have been attributed, it is to be observed that none of them have 

 even suggested that the doctrine of a " vital force " in its old sense 



