SCHIZOPHYTA SCHIZOPHYCEAE 187 



Gloeotrichia Pisum, (Ag.) Thur. 



It forms small green spherical bodies about 1 millimeter in diameter, floating 

 at various depths in the water. It consists of a mass of tapering threads ar- 

 ranged radially in the gelatinous matrix. The apices of the threads protrude 

 more or less, giving it a bristly appearance. The base of each filament contains 

 a heterocyst and above it a slender cylindrical spore and beyond it the ordinary 

 vegetative threads of the alga. 



According to Dr. Arthur it is common in Minnesota. He found it common 

 in Waterville, Lake Minnetonka, Lake Phelan in Minnesota and East Okoboji 

 Lake in Iowa. It was thought by the people of Waterville, Minnesota, that 

 this alga caused the death of cattle which drank the water. The history of these 

 cases is recorded by Dr. Arthur as follows : 



"That some of the animals had drunk of the water and scum a few hours only before 

 they died was positively known, and that all had done so seemed from circumstances quite 

 probable. After the most careful examination the only plausible hypothesis that could be 

 advanced to account for the death of the animals was that the alga present possessed some 

 toxic or other baneful properties sufficiently powerful to kill a cow in a half hour or more 

 after drinking freely of it. The well-established reputation of all the algae for innocuous- 

 ness made this hypothesis appear from the very first extremely improbable, but for want 

 of the slightest hint in any other direction it was thought worth while to bear it in mind, 

 and to investigate the matter further. 



About the middle of June, 1884, word was received that eight cattle had died on the 

 shore of Lake Tetonka. I at once started for Waterville, arriving on the twentieth and 

 found the algae less abundant than in 1882, but still making the water green some fifty 

 feet or more out from the shore toward which the wind had been blowing several hours. 

 Although the conditions were not the most favorable, yet it seemed best to attempt a direct 

 experiment by giving the animals water charged with algae. After much delay the services 

 of Prof. M. Stalker, state veterinarian of Iowa and professor of veterinary science in the 

 Iowa Agricultural College, were secured to conduct the experiment. A horse and calf were 

 employed. On June 30th, Prof. Stalker, with the assistance of Prof. Edward D. Porter 

 of the university of Minnesota, and in the presence of citizens of Waterville, made the 

 tests, the writer being unable to remain. The animals had not been permitted to drink 

 for some twenty- four hours previous, and were consequently thirsty enough to take a large 

 amount of water well charged with the algae. No bad results of any sort followed. 



The thorough and able manner in which the test was made leaves no reasonable doubt 

 of the perfect harmlessness of the algae in a growing condition. I append this last clause, 

 because the citizens of the place still believe that the algae are at the root of the trouble, 

 and that the test did not show it because they were not made at the right stage of their 

 occurrence. Although no sufficient study of the habits of this plant has yet been made to 

 enable one to speak with certainty, yet it does not appear from present data that in some 

 other stage it would give different results, unless it be when decaying, when it turns 

 brown or reddish brown and gives off a peculiar stench. At this time the microscope 

 shows the cells of the algae to be swarming with bacteria. Whether these are other than 

 the common and harmless bacteria of putrefaction it is at present impossible to say. The 

 probabilities are, however, entirely against the hypothesis that the decaying algae or the 

 accompanying bacteria have anything to do with the trouble. 



We are therefore obliged to sum up the economic part of this investigation by stating 

 that the death of the animals is probably not due to the suspected algae, and that no clue 

 to the real cause has yet been obtained." 



Dr. Arthur in a recent communication states that he has had no evidence 

 so far that these algae are poisonous. That the death of these animals was 

 probably due to bacteria found in the marshes. 



OTHER BLUE GREEN ALGAE 



of additional genera are known tc 

 waters; among them the Gloeocapsa with cells single or in groups surrounded 



Quite a number of additional genera are known to occur in our fresh 



