212 METHODS IN PLANT HISTOLOGY 



for class work will be found in an article by Dr. J. A. Nieuwland in 

 the Midland Naturalist, 1:85, 1909. 



Professor Klebs has shown that various phases in the life-histories 

 of many algae and fungi may be produced at will. By utilizing his re- 

 sults, the fruiting condition may be induced in many of the common 

 laboratory types. Knop's solution will be needed in most cases. A 

 stock solution which can be diluted as required may be made as follows : 



Potassium nitrate, KNO3 1 g- 



Magnesium sulphate, Mg804 1 g. 



Calcium nitrate, Ca(N03)2 3 g. 



Potassium phosphate, K2HPO4 1 g- 



Dissolve the first, second, and fourth ingredients in 1 liter of dis- 

 tilled water, and then add the calcium nitrate. A precipitate of cal- 

 cium phosphate will be formed. For practical purposes this may be 

 called a 0.6 per cent solution. Whenever a dilute solution is made 

 from the stock solution, the bottle must be shaken thoroughly in order 

 that a proper amount of the precipitate may be included in the diluted 

 solution. To make a 0.1 per cent solution, add 5 hters of distilled 

 water to 1 liter of the stock solution; for a 0.3 per cent solution, add 1 

 liter of distilled water to 1 liter of the stock solution, etc. 



The addition of a liter of a 0.2 per cent solution to 4 or 5 Hters of 

 water will often produce a more thrifty growth. Directions for inducing 

 reproductive phases are given in connection with the various types. 

 With a good supply of glass jars, plenty of Knop's solution, a reason- 

 able control over temperature, and the teacher's usual amount of pa- 

 tience, most laboratory types can be studied in the living condition at 

 all seasons of the year. 



Collecting algae need not be so laborious as most botanists make it. 

 Forms hke Spirogyra, Zygnema, Cladophora, Vaucheria, and Hydro- 

 didyon may be rolled up in wet newspaper and carried in a botany can. 

 They suffer less from lack of water than from lack of air. Large quan- 

 tities of material can be brought in and transferred to water after reach- 

 ing the laboratory. Even after 24 hours in the wet paper, such forms 

 seem to suffer no damage. 



Permanent preparations are needed to show details which are not so 

 evident in the fresh material. The unicellular and filamentous mem- 

 bers, together with such forms as Volvox, are best prepared by the 

 Venetian turpentine method. The structure is so much more compli- 

 cated than in the Cyanophyceae that it demands far more care and 

 skill to make good preparations. 



