458 BULLETIN OF THE BUREAU OF FISHERIES 



NOTES ON OTHER UNICELLULAR PLANTS AND ANIMALS 



The flagellates Phseocystis and Halosphsera and the tintinnid infusorians and 



acantharian radiolarians are secondary in importance to the peridinians and diatoms 



in the plankton of the Gulf of Maine, but are still sufficiently abundant there at 



times to call for brief notice. The last two are grouped here with the phytoplankton 



for convenience sake, though they are animals and consequently consumers and 



not producers. 



PHSEOCYSTIS 



The brown unicellular alga Phseocystis is the only organism that we have ever 

 found rivaling the vernal flowerings of diatoms in the Gulf of Maine either in abun- 

 dance of floating vegetable matter produced or in actual numbers. Its identity is 

 established by the simple structure of its cells, together with their green color and 

 association into slimy colonies. But whether we have to do with Ph. pouchetii, Ph. 

 globosa, or with both these species, has not been determined, the precise character 

 by which the two are separable — i. e., the form of the colonies, whether lobate 

 {pouchetii) or globose as in globosa (Lemmermann, 190S) — having been destroyed 

 either by preservation or by the churning which they underwent in the nets. This 

 is unfortunate, because pouchetii, with a range hardly extending south of 55° N. 

 latitude in European waters, is decidedly a more northern form than globosa, which 

 occurs in maximum abundance in the southern part of the North Sea and in the 

 English Channel (Ostenfeld, 1910). 



The Gulf of Maine records for Phseocystis have been confined to April IS to 

 20, 1920, when it was sparsely represented in the western basin (station 20115) but 

 so plentiful off Cape Cod and in the southern part of Massachusetts Bay (stations 

 20116 to 20118) that the fine-meshed silk nets used on the surface were clogged 

 with its slimy masses after a few minutes towing, making it impossible to obtain a 

 representative catch of diatoms or of other members of the phytoplankton. The 

 Phseocystis colored the water brown; in fact, the appearance of the nets as they 

 are lifted dripping with brown slime of offensive odor betrays the presence of this 

 ulga at once. 



Plentiful though Phseocystis was at this time, its flowering period must have 

 been brief, because it was not found in the region in question three weeks earlier 

 (stations 20087 to 20090) or off Massachusetts Bay and Cape Cod two weeks later 

 (stations 20120 to 20125), and it was not found anywhere in the gulf during the first 

 weeks of May, 1915. 



These few records show that Phaeocystis fills much the same biologic niche in 

 American as in north European waters. The region of its occurrence in the gulf is 

 reconcilable, without discussion, with the neritic habit with which Gran (1902 and 

 1912) and Ostenfeld (1910) have credited it, and which its European distribution as a 

 whole demands, though it is not confined to the immediate neighborhood of the coast 

 in either side of the North Atlantic. It seems a regular event for Phaeocystis to 

 appear suddenly in tremendous quantities, and while its maximum flowering falls 

 later in the northern than in the southern part of its range, it is characteristic of it to 

 dominate the plankton for only a short time at any given region. Off the Norwegian 



