CHEMICAL BASIS OF THE ANIMAL BODY. 11.-, 



their supply of carbohydrate food. It might more probably have 

 IMM-H expected that they should be shielded as far as possible from 

 any avoidable excessive digestive labour by the presentation of a 

 diivrtly assimilable sugar. We cannot as yet offer any other ex- 

 planation of the observed facts than the one that since lactose is 

 incapable of diivet (alcoholic) fermentation, not only is the milk 

 while it is accumulated in the breast less liable to fermentative 

 decomposition, but also the tendency to fermentative disturban< 

 in the alimentary canal of the young animal is largely diminished. 

 Both saccharose (cane-sugar) and maltose 1 are similarly not 

 dirfctly fermentable, and both again in the adult are apparently 

 converted into fermentable dextrose during, or at least, immedi- 

 ately before, absorption. The subject is one which requires further 

 investigation. 



FATTY ACIDS AND FATS, THEIR DERIVATIVES 

 AND ALLIES. 



I. ACIDS OF THE ACETIC SERIES. 



General formula C,,H 2B +i.COOH (monobasic). 



This, which is one of the most complete homologous series of 

 organic chemistry, runs parallel to the series of monatoniic alco- 

 hols. Thus formic acid corresponds to methyl alcohol, acetic acid 

 to ethyl (ordinary) alcohol, and so on. The several acfds may 

 yarded as being derived from their respective alcohols by 

 simple oxidation taking place in two stages, the first yielding an 

 aldehyde, the second an acid by direct union of oxygen with the 

 aldehyde. 2 Thus with ethyl alcohol 



(i) CH, . CH 3 . OH + O = CH, . COH + H,O, 

 (ii) CH,.COH + = CH,.COOH 



The successive members differ in composition by CH 2 , and the 

 boiling points rise successively by about 19C. Similar rela- 

 tioii> hold good with regard to their melting-points and specific 

 gravities. The acid properties are strongest in those where n 

 he least value. The lowest members of the series are volatile 

 li | u ids, acting as powerful acids; these successively become less 



1 Horace Hrown Private communication to author. Cf. V. MeriiiR, '/A. f. 



:: I r, (1881), s 



-' The views as to the possiMe importance of the aldehydes have already been 

 referred to when treating of pn.teids (see p. 52). It is further interesting to notice 

 that a simple polymerisation, to which it is very prom-, of the lowest Imeth ) aldehyde 

 II i i "II. Mould yield a sulistamv h.-miiir the composition of a carholn drate. ThlB is 

 indeed a view which is held hy many as to the mode of formation of starch in plants. 

 Cf. Miller I' .in in 1880, Sec. 1, p. 726. 



