ino-t acti\c: What d<> you conclude from rc-ult- of experiments 

 a. 1>. c. and 1 : 



' >.\-iiliist-s. < ixidixing enxyme- existing in the cell- of organ- 

 i-m- are readily -olnblc in water. \ eatable cell- yield extract- 

 of -pccial o\idativc activity. The initially colorle-s surface of a 

 pared p..t;itn i- turned ln>\vn by the oxidation of paraoxy-phenyl 

 '.nets -uch a- tyro-iu in the potato-cells. The brown pigment 

 produced i- a melanin and the enxyme is lyrosina-c. Tyro-ina-e 

 ha- the po\\er of oxidixing oxidixable com]), mud-, like phenol, 

 added to the juice a- well a- the t\ ro-in already pre-ent in the juice. 

 Into each of eight test-tubes place 5 cc. of filtered potato juice, 

 made by -craping potatoe- on a grater, expressing and filtering the 

 re-ult through clue-e cloth; the -larch is allowed to -etile and tin 

 -upernatent fluid removed, filtered and used in the tests. I Place the 

 March in the \e--el dc-tined for it. to be later purified. i Treat the 

 portion- a- foll<>\\ - : 



a. 'ntato | ; .\tract -|- 5 drop- ( ,f toluol. 



b. -".xtract boiled, then cooled and 5 drops toluol added. 

 v. -".x tract 5 drop- m', lk'1. 



d. Extract + 5 drop-,,, f 10', |\< ill. 



e. -'.x tract -j- 5 drops phenol i i', i. 



l". -"xtract boiled, then cooled, and 5 drop- \< , phenol added. 

 ".\tract 5 drop- guaiac -olution. 



h. ; .x tract + 5 drops a-napthol + 5 drop- para-phenylene 

 tliamine -< ilutii !!. 



i. To another lube add water 5 drops u-napthol -j- 5 drops 

 para-phenylene diaminc -olution. 



Thoroughly -hake each mixture. Xotice any change- in 15 or 

 ,;o minutes \\here i- the color mo-t marked? \\"hy : Set aside 

 until the next laboratory |ieriod and record change- in each. The 

 r liio] i- adU-d a- a preservative. It \\oiild kill any cell- pre-ent 

 but doe- not de-lro\ the o\ida-e. I- the phenol a preservative: 

 b. i. and i are control experiment- for e and h re-pectively. Do 

 ou see why: .Vote that potato juice accelerate- a proces- which 

 take- place -louly in the ab-encc of potato juice, a- in i. 



''. ( utiiltts,- diitl ,i.vi<lii.\- t - in tininitil tissues. a. Tea-e finch 

 \\ith a pair of needle- p.irtim- of the s^l.'cn, H:\-r. linii/, kidncv, 

 and inn.",!,- oi tlu' t'rog. I'lace portion. ,,f the-e ti--ne- in a seric- 

 of \\atch gla--e- and add to each dilute IL< >,. \\'hich tissue gives 

 the nio-t ].ronounced i-atalytic action: 



lo a -imilar series of \\atch-gla--r- containing the -ame 



-4 



