and the Cause of Epidemic Disorders. 117 



in relation to their intimate composition, and under that of 

 the elementary composition of their proximate principles, if 

 resulting from the union of several of these principles ; this 

 study presupposes that they have been isolated from the liquid 

 in which they have been disseminated, and, hitherto, it is but 

 too true that but very feeble attempts have been made to suc- 

 ceed in any endeavours of this kind. Although it is confessed 

 that difficulties present themselves to the isolation of the glo- 

 bules, we cannot too much insist upon the advantage it would 

 be to the natm-al sciences were one and the same observer to 

 devote his efforts to the comparative study of all the globules 

 which are found in animal fluids, so that the analogies and 

 the differences which exist among them might be ascertained. 

 The experimenter should abstain from forming alliances of 

 identity, which are based only on form which, even on ac- 

 count of its simplicity, may belong to very different kinds of 

 bodies ; and he ought never to forget that the identity in na- 

 ture can never be demonstrated but where there is identity of 

 chemical properties, among which we comprehend elementary 

 composition. An observer might deduce many valuable con- 

 clusions from the use of reagents, and especially if he were 

 careful not to confound them with the phenomena which 

 might be produced by their action upon bodies dissolved in 

 liquid in which globules existed. 



From the preceding considerations, which have a direct 

 relation to questions concerning the nature of organic sub- 

 stances in general, we pass to the study of milk in particu- 

 lar, which is the special object of this report, and may con- 

 clude, 



1st, That not only is the analysis of healthy (normal) milk 

 wanting, but even that the present analysis is not up to the 

 level of the labours which have put us in possession of the im- 

 mediate composition of butter, since it has been considered, 

 in all the analyses which have been made since these suc- 

 cessful labours, as a constant substance, and without taking 

 any account of the respective proportions of the stearin, the 

 olein, and the butyrin, and also of the caproine and caprine 

 which form it. 



