114 I.ACTOSK. 



Fhenyl-lactosazonc. C'. J4 1 f 82 N 4 0,. 



This compound of lactose with pheiiyl-hydrazin is formed under 

 conditions similar to those already described for the preparation 

 of the analogous compound of dextrose. It is soluble in 80 90 

 parts of boiling water and melts at about 200. It crystallises 

 readily in the form of yellow needles which, unlike the crystals 

 of phenyl-maltosazone, are usually aggregated into clusters. 



Lactose is readily capable of undergoing a direct lactic fermen- 

 tation and this occurs characteristically in souring milk. The 

 exciting cause is doubtless ordinarily an organised ferment, but 

 there is also some evidence of the existence in the alimentary 

 canal of an enzyme which can effect the same conversion. The 

 circumstances and products of the conversion are the same as for 

 dextrose and saccharose. 



Although isolated lactose is unaffected by yeast, milk itself is cap- 

 able of undergoing, under the influence of certain ferments, an 

 alcoholic fermentation, and this has been employed from very early 

 times by the inhabitants of certain districts of Russia in the prepara- 

 tion of Kumys and Kephir. from niare's-rnilk. Of late years these 

 fluids have attracted much attention in virtue of their supposed thera- 

 peutic action in certain wasting diseases. Very little is as yet known 

 as to the real nature of the changes which occur during the fermenta- 

 tion, but they are probably extremely complex and due to the presence 

 of several organised ferments. 1 Kephir ferment is a commercial 

 article in Russia, obtainable at the apothecaries. 



The non-assimilability of saccharose and maltose has already 

 been referred to, and experiment has shown that lactose is simi- 

 larly incapable of assimilation, for when injected into the blood- 

 vessels it appears unaltered in the urine. 2 It is therefore 

 presumably changed in the alimentary canal into some form of 

 sugar which is assimilable, it may be into dextrose and galactose. 

 It does not appear that any such conversion can be markedly 

 observed, if at all, under the action of any of the secretions of the 

 alimentary canal ; hence the change may more probably take place, 

 as in the case of maltose, rather during than before the passage of 

 the sugar through the intestinal walls. 



This non-assimilability of lactose is certainly remarkable when 

 it is remembered that it is in this form that young animals receive 



1 There is an extensive literature on this subject, of which the following are of 

 most comprehensive interest. Biel, Unters. uber den Kunu/s, Wien, 1874, and St. 

 Petersburg, 1881. Abst. in Maly's Benefit. 1874, p. 166, 1886, p. 159. Struve, Ber. 

 d. d. chem. Gesell. Jahrg. 1884, Sn. 314, 1364. Krannhals, Deutsch. Arch. f. klin. Med. 

 Bd. xxxv. (1884), S. 18. Hammarsten (Swedish). See Abst. in Maly's Benefit. 

 1886, p. 163. 



2 Dastre, Compt. Rend. T. xcvi. (1883), p. 932. Compl. Rend. Soc. Biol. (9), T. I. 

 (1889), p. 145. De Jong (Dutch Diss.). See Maly's Bericht, 1886, p. 445 



