ON ACTINOCOCCUS AND PHYLLOPHORA. 177 



surrounded by a very thin membrane, their cell-contents consisting 

 of a very finely divided rhodoplastid and numerous starch-grains. 



On arriving at maturity the nemathecia break up, the tetraspores 

 are set free and presumably germinate. It is impossible as yet to say 

 what actually is the fate of these tetraspores of Actinococcus subcutaneus, 

 after they have been set free from the parasitic nemathecium. Do they 

 germinate on another host and there form sexual plants with antheridia 

 and procarpia 1 



The tetraspores ripen in December and January aud shortly after are 

 discharged from the nemathecia, some of the latter apparently con- 

 tinuing to vegetate for some time. With the appearance of the 

 spermophores in the following autumn, we again find the parasite 

 entering the host-plant. What have the spores been doing in the 

 meantime 1 From what has already been said, it is not unlikely that 

 what we see germinating on Phyll. Brodiaei in the autumn is really a 

 carpospore. 



It has been possible to follow out the germination of the tetraspores 



of our species of Actinococcus. Briefly the results obtained were the 



following (2, pp. 25 — -27, Fig. 32, 33). The tetraspores, derived from 



the nemathecia of A ctinococcus subcutaneus, were sown on sterilized and 



purified parchment-paper. The whole was put in a small glass vessel 



filled with filtered seawater. Several cultures were started. The 



spores germinated, and in parts remained in a living condition for 



nearly two years. The products of germination took the form of small 



protonema-like organisms. The largest of these consisted of uniserial 



filaments and larger aggregations of cells, which at the time I took to 



be the rudimentary basal attachment-disks of Phyll. Brodiaei : it 



consisted altogether of upwards of 250 cells. As yet it still remains to 



be seen what actually becomes of these products of germination. 



Possibly they would normally have attacked a new host, be this Phyll. 



Brodiaei or some perfectly different plant, on which ultimately the 



carpospores would possibly be formed. The carpospores perhaps, one 



might almost say probably, germinate on Phyll. Brodiaei, and 



eventually give rise to the nemathecia of Actinococcus subcutaneus. 



It is not to be wondered at that the parasite should be able to live 



separately for nearly two years in an artificial culture, when it is borne 



in mind that its cells contain rhodoplastids. The long filaments are 



probably searching for a suitable substratum, whereas the larger 



L 



