IN VEGETABLE BIOLOGY. 215 



Experiments were also made with stems of Maize and Vegetable- 

 Marrow, but derived from spirit-kept material. The result 

 showed that even after three weeks' action of absolute alcohol, in 

 addition to a long sojourn in spirit, the proteid reactions were 

 yielded in the normal fashion. Thus, out of seventeen cases 



Ma 



material) 



one who has tried these tests, using thin sections, knows that he 

 must expect occasionally to fail with them. 



* 



II. Sections kept three weeks in Hydrochloric Acid (50 per 



cent, solution of the strong acid). 

 Ash (M). Normal reaction. 



(X). Ditto. 



(R). Ditto. 

 Fig (M). Normal reaction. 



(X). Ditto, with a faint reaction in hard bast. 

 (R). Normal. 

 Hosa canina (M). Reaction normal. 



(X). Good reaction xylem : extraxylemic tissues 



not noted (apparently they must have 

 *rot separated from the xylem and so 



sep 



escaped observation). 

 (R). Normal. 

 Arundo Phragmites (M). Good reaction as usual. 



(X). Ditto. 

 (R). Failed, except at one corner of the 



section. 



Maize (M), (X), and (R). Quite normal. 



Isoetes lacustris (stem) (M). Good reaction in xylem of great 

 central vascular bundle, as also of leaf-trace bundles: in 

 one case meristem-walls reacted well, but the test failed 

 with another section. Fresh sections (derived from spirit- 

 material) give good reaction in xylem and (generally) in 

 meristem. 



"We may hence conclude either that tyrosin is absent, or that it 

 has entered into some insoluble compound with a substance or 

 substances in the wall. 



