of the vicinity of Aberdeen. 9 



sional moistening with sea- water is all that is necessary for the 

 development of this species, and hence it is mostly found at high- 

 water mark. Dr. Montagne has found both kinds of fructifica- 

 tion in the same receptacle. The basisperms in the course of their 

 development undergo several changes : these may be easily traced 

 in F. serratus and F. canaliculatus. In the former we first ob- 

 serve large cells with several nuclei in their interior ; these rapidly 

 increase in size ; the parent cells now appear compound and in 

 course of time disappear, the young cells becoming free. Figs. 1, 

 3, 3, 4 in Plate I. represent these stages in the species alluded to. 

 In F. canaliculatus the young cells are not so numerous as in the 

 former case. 



Some time ago a few experiments were made for the purpose 

 of ascertaining the mode of germination in the last species. A 

 considerable quantity of its seeds were placed on shps of glass, 

 to which they readily adhered ; these were kept immersed in sea- 

 water, which was renewed every four or five days. The experi- 

 ments were conducted in a room at a moderate temperature, and 

 in the month of December. In about three weeks the seeds were 

 found to have undergone a change of form ; from triangular with 

 rounded angles they had become spherical. In the next stage a 

 slight swelling was observed on many of them, and at a more ad- 

 vanced period there issued at this place several minute transpa- 

 rent filaments, never exceeding four in number from the same 

 seed ; one or more of these had usually made greater progress 

 than the others. In their interior was seen a granular matter of 

 a pale yellow colour. The observations were interrupted at a 

 more advanced stage, when the filaments appeared to have be- 

 come coherent at their bases. By careful examination under the 

 microscope, it was found that each seed consists of two coats, the 

 inner the most delicate of the two and containing a granular mat- 

 ter ; the filaments appeared to be prolongations of it, and to have 

 burst the outer and stronger membrane. 



Figs. 5, 6, 7, 8 represent the germination at different periods. 

 The receptacles containing the acrospermal conceptacles, gene- 

 rally when newly collected, have an orange-yellow colour, and 

 after some hours an orange mucus exudes from the pores, which 

 on examination with the microscope will be found to consist of 

 acrosperms. The cell in which each of these bodies is included 

 is for the most part so transparent, that it is difficult to detect 

 the presence of any enclosing membrane, more especially if 

 viewed in a di'op of sea-water, the medium which ought always 

 to be used in examining the structure of marine species. On 

 placing them in fresh water the containing cell is seen to burst, 

 and the enclosed acrosperms are expelled with considerable force. 

 Each body is composed of a simple membrane containing small 



