182 BOTANICAL GAZETTE [September 



stains as deeply as does the cell wall of the mother cell. The 

 oval nucleus stains deeply and soon occupies one end of the pro- 

 toplast (fig. 27). At the other end, a dark spot appears in the 

 cytoplasm — the blepharoplast — which gives rise to the cilia. The 

 nucleus in its growth elongates, soon making a turn around the 

 cytoplasm. The cilia are not easily distinguished from the coils of 



the nucleus. 



asm. anterior to the 



from which the cilia extend, a rounded mass is left at the posterior 

 end of the sperm. This is a mechanical hindrance to the movement 

 of the sperms when the cell walls are transformed into a mucilagi- 

 nous substance and the sperm is often twisted into small spirals 

 on its own axis (fig. 27). These disappear as soon as space is given, 

 and at the time of shedding the mass of cytoplasm at the base is 

 also gone. The body of the sperm is very long and averages about 



the 



sperm 



measurements of the longest sperms 



I the antheridium before it had burst natu 

 shed in the field thev have grown somewhat 



Probably 



The antheridia begin to form early in the spring. They develop 

 in acropetal succession until August, when many of the branches, 

 as has been noted (Leitgeb, Campbell), continue vegetative 

 growth. The last antheridium formed is sometimes not imbedded, 

 but superficial, owing to the rapid elongation of the thallus. 



Archegonia. — Aneura pinguis bears its archegonia also on 

 the dorsal surface of distinct lateral branches (fig. 28). Such plants 

 have conspicuously light green filamentous outgrowths, varying in 

 length and width on the lateral margins. These are caused by the 

 more rapid growth of the thallus edges of the main axis or of the 

 lateral branch. Again, there may be from one to three branch 

 primordia; usually, however, one outstrips the others in develop- 

 ment. Like the antheridia, the archegonia are regularly arranged 

 in two rows, alternating according to the apical cell segmentation. 

 The division of the primary segment is as usual. The first dorsal 

 superficial cell is the archegonium initial. In order of development 

 it follows the general liverwort type. Three vertical intersecting 



from which 



horizontal 



\~S 



