CHEMICAL I'.ASIS OF THE ANIMAL I'.nDV. 



ism of jilants; l)iit as yet tin- aldeh\ dc of aspartic acid has not 

 been prepared by any chemical means, and P>aum:iim l has cast 

 great doubt <>n the reliability of the methods by which tin- above 

 authors have endeavoured to prove the existence of aldehydes in 

 the protoplasm of the living plant cells. And it is probably sig- 

 nificant that the reactions by which the presence of the aldehydes 

 i^ supposed to be shown are only well marked in the case of the 

 cells nf the lowest plants; in the case of animal cells they are 

 more usually wanting. 



THK KN/YMI.S OK SOLUBLK I'N>I:I; AM/KM KKUMKNTS.* 



Chemists have for a long time been familiar with an extensive, 

 and still increasing class of reactions which occur solely, or in 

 ^ome cases most readily, in presence of minute quantities of some 

 < ubstance which does not itself appear to enter directly into the 



Mii : in other words the causative agent is found to have 

 it-elf undergone no obvious change during the reactions which it 

 has set up between the other sul tstances. Striking instances of 

 Mich reactions are observed in the preparation of ether from 

 alcohol by means of sulphuric acid and in the manufacture of 

 sulphuric acid itself. In the former case a small quantity of 

 sulphuric acid is theoretically able to convert an indefinitely 



quantity of alcohol into ether, and in practice the limit is 



mined simply by the occurrence of secondary decompoftitioiu 

 between the reagents. Similarly during the manufacture of sul- 

 phuric acid a minute quantity of nitric oxide suttices in the pres- 



of water to convert an indefinitely large amount of -ulphurons 

 anhydride into sulphuric acid. Of late years a large numl 

 reactions have been found to depend for their OOOUTTBl ..... upon the 



nee of the minutest traces of water; thus ,//// chlorine has 

 no action on dry sodium, and dry hydrochloric acid gas and 



'u do not react even when exposed to bright sunlight. 

 neither do ,//_// oxygen ami carbonic oxide explode on the passage 

 of an electric spark. The fact of immediate interest in each of 

 the aliove instances i- that a minute trace of the substance which 

 determines the occurrence "f the reaction is abl -luce 



change in an indefinitely large ma-< of the other reagent- without 

 ing any final alteration. Turning to t he cheini-t r\ 



1 rtln-.T's A f ,-h. H.I. \\iv (I8*-M. S. 4H( 



Cktm. IM. \ (18C 



: It :i|,|,r:irs :ul\ i-:il.l.- I'. n->- tin- t.-mi 'ni/Mi..-' iKnlin.. ' /. /.Ay*o/. 



];,| | i - .liiMi- mi..: t in. 'lit* fin- 



. -rallv, n-.TMii- tl ..... M.T naiin- "f ' f. rin.-nt ' f..r tin- >i i-'li M JMt 



iiirli it u;i> lir-t aj.|ilM-i|. If tlii IM^ .1 ...... it uill ! . ..n\ i-nii-nt t n- 



/.\ni.i|\-i- ' t-> ili'ii.iti- tli.- i-lian^f.* |ir>Mliin>i| l.y tin- <-iu.\ iiu- in tli. 

 -iiLsta'tircs, and t.. a|.|.ly tin- ti-rin ' f.Tiiinitati..ii ' f.tlM- a. tin ( the orgmnilH 

 nt- In tl, '* I" tin- <;.-rinaii ' F- rm. iitwirlaiMi:' 



>i..n 



..th.T -ii 



f.Tinrnt- 



an. I ' fiTtii<-iitatiii ' to M .ii 



