242 BOTANICAL GAZETTE [ocToRER 
and, as Sachs himself notes, the investigation of the apical cel- 
and its divisions has ceased to be regarded as affording a key to 
the explanation of the development of shoots. 
Assuming the correctness of Sachs’s law for the higher plants, 
if we attempt now to apply it to the case of the cell-division in 
sporanges we are confronted with many difficulties. 
First of all, these sporanges do not divide by successive 
bi-partitions as do the cells in the growing points referred to. 
Nor do they divide by simultaneous delimitation of the energids 
which, according to Sachs’s view, compose them. Their cleay- 
age is progressive, and the cleavage planes, as shown in sections, 
form no great series comparable to the anticlines and periclines 
which Sachs finds in a section of a root tip. In the cleavage of 
the sporange the principle of rectangular intersection is violated 
constantly, the angles of intersection of the cleavage planes 
showing no constancy whatever. It may be objected that the 
Sporange is not a growing organ, and hence its method of 
division should not be expected to conform to that of grOnms 
points. Growth is complete in the sporange before division 
begins, though it may recommence in the later stages of cleav- 
‘age in Pilobolus. The process in the sporange consists 1 
cutting up into cells a mass of protoplasm whose form has bet? 
already determined and its growth completed. Still, although 
Sachs states the principle of rectangular intersection for oer 
ing points, and conceives it as determining the arrangement © 
the cells in the growing point as it pushes forward in the elonga 
tion of the shoot, he always conceives the divisions as sre 
in these growing points after the essential embryonic growth 0 . 
the cell concerned is at an end. Growth of cells subsequent © 
division may, and generally does, in his opinion, distort the 
relations of the cleavage planes. : pe 
Sachs makes no attempt to include the multinucleated sp” 
th of the 
rangia in his discussion. Still he specifies the grow 
Siphonez (19, p- 100) as exceptional when compared 
irregular growth of many thallophytes, and considers night 
opment at their growing points as typical of that the Me 
with the 
