194 HOIMEISTER, ON 



arch of the apex of the archegonium multiply by division 

 which takes place by means of septa at right angles to the 

 outer surfaces. This process is especially remarkable in 

 Gymnogramma calomelanos (PI. XXV, fig. 7). Where the 

 neck of the archegonium consists of only four longitudinal 

 rows of cells the axile canal is manifestly formed by the 

 parting asunder of the angles of contact of the latter cells. 

 The membranes of the cells grow in the direction of tan- 

 gents to the cylindrical organ : thus an intercellular space 

 originates between them, which is often of considerable 

 width. The process commences underneath the arch of the 

 apex of the archegonium and proceeds from thence to its 

 base (PL XXV, fig. 4). When the neck of the archegonium 

 is traversed by an axile string of cells the canal can only be 

 produced by the dissolution of the transverse septa of these 

 cells. In this case also the dissolution is preceded by an 

 increase in growth of the peripheral cells in a tangential 

 direction, which is especially remarkable at the apex of the 

 neck of the archegonium, so that the axile string of cells 

 assumes a clavate form (PI. XXV, figs. 5, 7). 



Within the canal of the neck of the archegonium, whilst 

 the latter is still closed at the apex, there is sometimes (but 

 by no means always) to be found an elongated vermiform 

 body, of a finely granular, tough, gelatinous consistence, 

 club-shaped at the upper, and tapering towards the lower 

 end. At other times there may be seen several similar 

 bodies within the canal, of which the uppermost are 

 usually elongated, and the lower ones spherical. The re- 

 verse is however sometimes the case, the lower bodies being 

 sometimes longer than the upper ones (PL XXV, figs. 7, 

 11). These bodies are very probably nothing more than 

 the altered contents of the cells of the axile string of the 

 neck of the archegonium, which upon the dissolution of the 

 transverse septa run together more or less completely into 

 one mass. The elongated clavate form of the upper of these 

 bodies (a form which is of frequent occurrence when 

 several of such bodies are present) probably results from the 

 fact that in this case also the formation of the canal of the 

 neck, the dissolution of the transverse septa of the axile 

 row of cells, and consequently also the flowing together of 



