IV. THE ANTHOCEROTRS 131 



cells the four primary divisicjiis arc still ])lainly discernible, and 

 the individual sperm cells are cul)ical in form. In the per- 

 ipheral cells hardly less reg^ularity is ojjservahle. Exce])t near 

 the apex none but radial walls are formed after the first trans- 

 verse wall has divided the body of the antheridium into two 

 tiers, and when complete the wall consists oi three well- 

 marked transverse rows of cells, the lower being- derived from 

 the uppermost tier of stalk cells. At the apex the cells are not 

 quite so regular (Figs. D, E). In its younger stages the 

 antheridium is very transparent and perfectly colourless. In 

 each peripheral cell a chloroplast is evident, but at this stage 

 it is quite colourless and the nucleus is very easily seen in close 

 contact with it. As the antheridium grows the chloroplasts 

 develop with it, becoming much larger and elongated in shape, 

 and at the same time develop chlorophyll. The mature chloro- 

 plast is a flattened plate that nearly covers one side of the cell, 

 and its colour has changed from green to a bright orange as in 

 the antheridium of many Mosses. The sperm cells are dis- 

 charged through an opening formed by the separation of the 

 apical cells of the antheridium. These cells do not become 

 detached, but return to their original position, so that the 

 empty antheridium has its wall apparently intact. The sperma- 

 tozoids are small and entirely like those of the other Hepaticae. 



Leitgeb ((7), v., p. 19) found in abnormal cases that the 

 antheridia may arise superficially, as in the typical Hepaticse. 

 Lampa ( i ) describes a similar exogenous origin for the 

 antheridium, but Howe (5) has questioned the accuracy of 

 her statements, and thinks that the supposed antheridia were 

 tubers, as Frau Lampa's figures do not agree with the structure 

 of the typical antheridium. Whether this exogenous develop- 

 ment of the antheridium is a reversion to a primitive condition 

 is impossible to decide, but it is possible that such is the case. 



At first the cell from which the antheridial complex arises 

 is not separated from its neighbours by any space. About 

 the time that the first divisions in it are formed, the young 

 antheridial cells begin to round off and separate from the 

 cells above them. With the growth of the surrounding cells 

 this is increased, so that before the divisions in the separate 

 cells begin, the group of papillate cells is surrounded by a 

 cavity of considerable size. To judge by the readiness with 

 which the w^alls of the cavity stain, it is probable that the 



