Uieridial spots in P. leucostiiia. They were found lo consisl of aniheridia earlier in 

 their development than Ihe surrounding aniheridia, wliicli were still in division. 



As first shown by BriiiTHoi.i) (I8(S0 and 1882), the spennatia allach themselves 

 to the female portions of the frond, and a tine fertilization canal is formed through 

 the wall of the carpogonium-cell. These lertilizalion canals contain a Ihin strand 

 of protoplasm, which is still lo be seen a long time after the fertilization, while 

 the exhausted sperniatium quickly disappears. Their number is often remarkably 



great , 



much greater than that of 



^988 



8 



the carpogonia (Fig. 5 A — C). It is 

 evidentl}^ a very common case thai 

 several fertilization tubes are intro- 

 duced lo one carpogonium. 



The fertilised carpogonium 

 divides, as is well known, by a 

 transverse wall; thereafter follow 

 often one or two further transverse 

 walls, whereupon arises a 'A- or 4- 

 celled prismatic body wich there- 

 after may be further divided by 

 differently orientated walls (hg. 5 

 D, F). Such divisions result no 

 doubt in cystocarps with numerous 

 carpospores, while the typical case 

 is regarded to be eight carpospores 

 in two layers. Extraordinarily large 

 cystocarps, containing a great num- 

 ber of spores, were found in speci- 

 mens collected in the harbour of 

 Skagen in April, the frond of which 

 was unusually thick, 90 to llo/^ (fig. 

 5 D^F). Comp. Bertholi) (1882) 

 fig. 10. 



In a number of specimens (r)2) 

 collected in March on groins near Thyboron , nearly all belonging to I. linearis, a 

 few to f. laciniata, I found only cystocarps containing about 8 car|)Ospores arranged 

 in two layers, but in no case could spermatia or fertilization tubes be observed, 

 and none of the plants contained antheridia. As the spores in all cases examined 

 resulted from a division parallel to the frond, it may be supposed that we have 

 here a case of apogamy, if it should not be found that the monospores can result 

 also from such divisions. 



The development of Ihe cystocarps is as a rule uniformly progressive from 

 the margin of the frond inward. Someliincs, howevci-, the nialuralion lakes place 



D 



I^lg. 5. 



I'oriilnirii iniibilicalis. A -li, specimens IVdiii Ihe li;irboiir (il SUagen, 

 .hily. .1 and B, parts of IVonil seen from llie siuMace : the eell-walls 

 and, at a hifiher level, tlie fertilization luljes and in ,1 a s])ermalinm 

 are shown. C, part of fron{l with ferlili/.alion-lnbes and oysloearps 

 in transverse section. A—(" '.>'M) : 1. D and E, hansverse seclif)ns of 

 Irond Willi cystocarjis Ironi Ihe same locality. .Viii'il. 2:!():1. 1'. in- 

 com|)lelely ilivided cyslocai'p, I'rederilishavn December. ."il)(l:1. 



