Formed Constituents of Organisms 149 



the oogonial or antheridial wall cells of Nitella, in the capsular 

 wall cells of some mosses, in the seed-coat cells of cycads, in 

 the red fruits of many of the higher seed plants. 



Again mannite is met with amongst such alg?e as Laminaria, 

 Halidrys, and Fiicus, is widely distributed amongst the fungi, 

 is found in roots of celery and carrot, in tubers of aconite, in 

 the liquorice (^^, 1: 361), and in the rind of several "widely 

 separated groups of flowering plants (p. 377). 



Oxalate of lime crystals occur in species of Spirogyra, in 

 many conifers, in some monocotyledonous and dicotyledonous 

 families or genera, though not at all in other of these groups. 

 In crystallization shape, also, they are equally diverse in their 

 characters. Even the relative distribution of the needle crys- 

 tals or raphides is often highly suggestive. 



Again the brown pigment of indurated walls is frequent 

 in fungoid spores, in the spores of liverworts, mosses, and ferns, 

 in the cells of many seeds, and in the strengthening tissues 

 of seed plants. But amongst soft and shade loving plants, in 

 aquatic plants, and in many xerophytes it is absent or rare. 



Similar cases might be cited as to the sporadic occurrence 

 of certain giucosides, of certain alkaloids, and other bodies. 

 Scores of examples that illustrate like appearance and disap- 

 pearance of cell constituents can readily be demonstrated by 

 all, with aid of such works as those of Wiesner (66), Zopf 

 (29: 386-464), or Czapek (2J^). 



But, even if we confine attention to the higher flowering 

 plants, many equally striking results are obtained. Thus it 

 is true of nearly every large — and of not a few small — families 

 of the dicotyledonous Apopetala? and Sympetalae, as of the 

 higher monocotyledons, that, though showing little affinity 

 often in taxonomic value of their flower, they all start in their 

 primitive genera or species with greenish yellow or yellow 

 floral coverings, but show steady advance to yellow-red or 

 pink-red, then to pink-crimson or pink-purple, and from such 

 to purple-blue, while many of the families advance to pure 

 blue. Though minor variations at times seem to cause excep- 

 tions to the rule, the author has proved by calculations that 



