THE TRANSLOCATION OF PROTOPLASM 159 



a hypha of one of the Ascomycetes, Basidiomycetes, or Fungi 

 Imperfecti, the mass of protoplasm is much constricted at intervals 

 owing to the presence of the small-pored septa. The presence or 

 absence of septa in a hypha is correlated with differences in the 

 reaction of the protoplasm in respect to an injury which causes part 

 of the protoplasm to die. To elucidate this statement let us suppose 

 that one breaks into two pieces first a hypha of a Phycomycete, 

 e.g. Rhizopus nigricans, and then a hypha of one of the Higher 

 Fungi, e.g. Pyronema confluens, and compares the reactions of the 

 remaining living portions of the two hyphae. When a hypha of 

 a Phycomycete is broken across, from each broken part some of the 

 protoplasm escapes and forms a rounded mass at the opening. This 

 ball of protoplasm and also some of the protoplasm remaining in 

 the end of the hypha cpiickly coagulates and dies (Fig. 80, A). The 

 dying back of protoplasm in the hypha continues for some time 

 (B, C, D) and then ceases, with the result that the broken end of 

 the hypha becomes plugged up with an elongated cylindrical 

 coagulum. The living and the dead protoplasm in the hypha 

 remain in contact with one another for a long time and no septum 

 is formed between them (E, F, G). Finally, when the living part 

 of the hypha has become highly vacuolated, a septum may be formed 

 within it near to (H, I, J), or at some distance from, the junction 

 of the living and the dead protoplasm. How far along the hypha 

 the effect of the wound will travel in any particular case can not 

 be predicted. On the other hand, when a hypha of an Ascomycete, 

 a Basidiomycete, or a Fungus Imperfectus is broken across, as we 

 know from experiments already described, the protoplasm of the 

 broken cell dies as a whole up to each septum and at the two septa 

 the effect of the injury ceases (c/. Fig. 70, A, p. 137) : the two cells 

 adjacent to the broken cell remain living. Evidently, a septum in 

 these fungi serves to protect a living cell against the effects of the 

 death of an adjacent cell. When one cell in a septate hypha is broken 

 across and killed, the two living masses of protoplasm left behind 

 are each bounded and protected from the first by an old septum, 

 and no new cross-walls are constructed. We thus see that the 

 septa in the mycelia of the Higher Fungi play a very important part 

 in limiting the deleterious effects of wounds. 



