1909] COPELAND— PERIODICITY IN SPIROGYRA 15 





April 27 S. quadrata was found conjugating abundantly. This one 

 was followed by others until twelve different species had matured and 

 disappeared. At first all material was brought to the laboratory in 

 small jars and then examined, but this method was by no means 

 satisfactory. A microscope together with a crude temporary stand 

 was added to my collecting outfit, and an examination of all material 

 was made on the spot. There are so many chances of collecting 

 worthless material that no other method was found which would give 

 definite results. 



The first task was to locate Spirogyra in a number of different 

 localities with different conditions of environment. Accordingly 

 a few localities were selected varying from a few rods to twelve 

 miles apart. Within these regions 40 different places were selected 

 which could be visited frequently and studied with care. Some 

 were in open places, while others were in deep shadow; some were 

 in pure running water, others in filthy stagnant pools; some with 

 numerous other algae, others almost alone; and under many other 

 conditions. 



For identification of species some of the material was usually 

 killed in the field as soon as collected. From 2 to 4 per cent, solu- 

 tion of formalin was used for this purpose when larger masses were 

 killed, but in most cases chromacetic solution was used according 

 to the formula given in Chamberlain's Methods in pi 



°gy> P- 139 (chromic acid i gr , glacial acetic acid 4", water 400°' 

 Several stains were used, but Haidenhain's iron-hematoxylin was 

 most satisfactory. Some of the specimens stained in this way were 

 afterward mounted in glycerin, others in balsam, and others in Vene- 

 tian turpentine. I found the balsam more satisfactory than the 

 turpentine, but excellent preparations were obtained by using the 

 Venetian turpentine method recommended by Chamberlain (stain 

 with magdala red and anilin blue and mount in Venetian turpentine). 

 Stained preparations in glycerin were most quickly obtained by tak- 

 mg the material as soon as washed from the chromacetic solution, 

 transferring it to a 10 per cent, solution of glycerin to which was 

 added 2 or 3 drops of Ehrlich's blood stain, and allowing it to con- 



centrate. 



method 



mon 



This method 



