86 



OFFICE OF THE MILK AND ENZYME. 



The office of this milk in the economy of the papaw is not easy to 

 explain. Parkin [Pharmaceutical Journal, 1578, page 337) states : — 

 "The most important functioi of such a latex is that of holding water 

 in reserve." This seems hardly possible in respect to this plant because 

 all tissues of the plant are filled with a watery fluid, so much so that 

 they flow upon cutting, and it is hardly possible that the tree is de- 

 pendent upon the milky juice for a supply of moisture. The native 

 observers suggest that the milk has to do solely with the ripening of 

 the fruit, and it is true that as the fruit ripens it is in all parts per- 

 meated with the milk, and as a consequence the starch compounds are 

 changed to sugar ; the proteids are peptonized and the flavour mel- 

 lowed. But it would seem to be a prodigious waste of energy if this 

 ripening action was the only action of the milk and its enzyme con- 

 tents. ^^ 



"We do know, however, that this latex is the carder of enzymes, and 

 that in plant life certain enzymes play an important part in incorporat- 

 ing material for the growth of t e living j-ubstance or of preparing 

 material brought to it, so that it may be capable of such incorporation. 

 Again, they bring about decompositions which supply the energy 

 needed for the maintenance of vital processes. In other words, these 

 enzymes digest and prepare food for plant life and growth. 



J. Reynolds Green has shown that in the process of nutrition in 

 plants, when the constructive processes are active, an excess of material 

 is elaborated and deposited in temporary reservoirs This material is 

 utilized by a process of digestion brought about by the agents of 

 enzymes or ferments which are formed to digest these deposited 

 materials. From many plants we have been able t » separate 

 diastasic, proteolytic, glucosidal, emulsifying and other ferments. 



The papaw is a plant of quick growth. It rapidly appropriates and 

 converis decaying vegetation. Its best fertilizers have been found to 

 be dead vegetable and animal matter, h luse waste, etc. This suggests 

 that the presence of this abundance of enzymic power is necessary for 

 the digestion and conversion of plant-food material, and that the 

 material is prepared for incorporation in the living plant by the 

 enzymes present in the latex. 



The milky juice of the papaw can therefore be imagined as quite akin 

 to the gastric or pancreatic juice of the animal organism. The ducts 

 through which this latex flows are possibly digestive tracts ; their coo- 

 tents, an emulsion of partially digested proteid and other material, 

 under transformation preparatory to ultima' e assimilation. 



Corrosive Properties of the Latex. — The corrosive action of the latex 

 has been recorded ; all species have this property in some degree. 

 Persons who handle the green fruit in the preparation of pickles are 

 troubled with raw and bleeding fingers and are forced to abandon the 

 work. The fresh latex will irritate the mucous membrane and its 

 continuous use is in some instance -i very escharotic This property 

 seems more manifest in certain isolated plants of apparently the same 



(11) AsBuming that there is at the lowest estimate, 100 ounces of latex in a 

 tree, we would have twenty ounces of dried material capable of converting about 

 3,000 pounds of proteids. 



