OF SOUTH AUSTRALIA. 
21 
a quantity of TJlva for his marine aquarium, the fronds being well grown 
aid of a beautiful deep green colour. The plants were put into the water 
at night, and quite early next morning the water of the aquarium had a 
turbid appearance. “As the sun came to shine on the side of the 
aquarium, I noticed a band of grey green matter bordering the side in the 
sunshine, and adhering, apparently, to the glass at the upper surface of 
the water, and the aquarium was clear. When the green band was touched 
there seemed to be a dispersal of the material but it readily came together 
pig i . — jjiva lactuca — (a) Frond with perforations; (b) vegetative cells: 
(c) cells forming zoospores, some emptied; (d) zoospores 
developing into thallus; (e) cross section of frond. 
again. ’ ’ Under the microscope there were seen to be two kinds of spores. 
“One was quite round and moved slowly with an irregular rolling motion. 
I could not detect cilia although the motion would indicate their presence. ’ ’ 
The other kind was smaller, conical, and with cilia at the apex, and very 
active. ‘ ‘ On further examination I found some of these zoospores clinging 
to the broken walls of the cells, both forms, and exhibiting active exertions 
to be free.” He did not, apparently, observe the union of the gametes. 
The so-called “species” of TJlva are all so unstable that they are probably 
best considered as races of one species. One may tabulate forms at one’s 
pleasure. 
