TYPICAL, RUDIMENTARY, AND REDUCED FORMS. 



a purely external examination, would exhibit all possible transitional forms between the 

 organisation of the germinating Almond and the Boirydium; but for a physiologically 

 correct comprehension of the actual state of affairs we scarcely require this aid, since 

 we can prove that that part of either plant which penetrates into the substratum, and 

 equally that rising above the substratum, undertakes in both cases essentially the 

 same functions for the whole plant, in spite of all difference of form, and is to this 

 end endowed with the same kinds of irritability. 



In order to obtain at once more general points of view for physiological 

 organography, we will take into consideration yet a third example, a plant of structure 

 equally simple to that of Boirydium, which also consists simply of a single, branched, 

 tubular cell, a mould-fungus of the 

 Mucor group, which is represented 

 in Fig. 3. The part {rri), with its 

 thousands of branches, has arisen 

 from the germinating spore, and 

 has extended in the substratum 

 (e.g. moist bread, the flesh of an 

 apple, &c.). After some time, there 

 grow forth from the main arms of 

 this branch-system thicker simple 

 tubes, which rise above the sub- 

 stratum, swell up in a globular 

 m anner at their ends, and develope 

 reproductive organs in these spo- 

 rangia. Our whole Mucor plant 

 is devoid of chlorophyll, and is 

 therefore unable to produce or- 

 ganic vegetable substance by de- 

 composition of carbon dioxide; on 

 the contrary it absorbs it for its de- 

 velopment out of the substratum, 

 that is, by means of the portion 

 m (contained in the substratum) 

 which, in spite of its different or- 

 ganisation, behaves itself, physio- 

 logically, exactly as the root of the 



Boirydium and of the Almond, since it penetrates into the substratum, urged by the 

 same kind of irritability, and absorbs water and nutritive matters from it. We are 

 therefore completely justified in regarding this portion of our fungus, distinguished 

 by botanists as the mycelium, as its root, and accordingly the fruit-bearing portions, 

 protruding above the substratum, appear as shoots ; it is true they show, as already 

 said, an essential difference from the forms of shoot hitherto considered, inasmuch as 

 they are devoid of the capacity of producing vegetable substance from carbon dioxide, 

 since they contain no chlorophyll; instead of this, however, the other property of the 

 shoot — to bear reproductive organs — has been preserved to them. 



We have started in our organographical consideration, as also appears in the 



Fig. 3, — Pkycomyces nitens. tn mycelium (root) grown in gelatine ; 

 g conidiophores, rising above the substratum. 



