144 



Mycologia 



studying Mucor mucedo, made the following statement : " Die 

 Scheidewand ist nicht etwa urspriinglich horizontal und erhallt ihre 

 gewolbte Form durch Dehnung unter dem einfluss des Druckes der 

 Fliissigkeitssaiile im Fruchttrager, wie mehrfach angegeben wird, 

 sie hat in der ersten Anlage die gewolbte Gestalt, die nachtraglich 

 nur unwesentlich modificirt wird." 



Mucor mucedo and Rhizopus have been used as types not only 

 in advanced and elementary textbooks of botany, but in many so- 

 called textbooks of biology. Here especially the desire to elabo- 

 rate in detail on the life processes beyond what is in the literature 

 has led to many false statements, which should certainly be cor- 

 rected in the interest of sound teaching. Illustrations of such in- 

 correct statements are found in the following texts : 



Bessey (4) figures and describes the development of the spo- 

 rangium of Mucor mucedo as follows : ". . . the vertical hyphae 

 which are filled with protoplasm become enlarged at the top and 

 in each a transverse partition forms (A, a, fig. 159), the portion 

 above the partition (b, fig. 159) becomes larger, and at the same 

 time the transverse partition arches up (B, a, fig. 159), finally 

 appearing like an extension of the hypha, and is then called the 

 columella (C, a, fig. 159)." Reynolds Green (21), referring to 

 Mucor mucedo, states : " A septum is formed close to the apex of 

 the hypha, cutting off a small head, which grows and becomes 

 globular. The lower cell grows also and projects into the swollen 

 portion, forming a columella." Parker (40), referring to Mucor, 

 states : ". . . The sporangium continues to grow, and as it does so 

 the septum becomes more and more convex upwards, finally taking 

 the form of a short club-shaped projection, the columella, extend- 

 ing into the interior of the sporangium." Atkinson (1) writes: 

 " . . .at the same time that this end cell is enlarging the cross wall 

 is arching up into the interior. This forms the columella." Coul- 

 ter, Barnes and Cowles (13), referring to the Mucorales, write: 

 " After the terminal sporangium cell is cut off, the separating wall 

 bulges into the sporangium cavity, forming the so-called columella." 

 Bigelow (5) incorporates in his text Parker's faulty figure of the 

 method of the columella formation. Nathansohn (38) states: 

 "... durch eine QuerWand schniirt sich an deren Spitze eine 



