Study of Spirogyra nitida. 213 



Micro-Chemical Investigation. 



Fresh, healthy material was examined under the micro- 

 scope for the substances usually present in plant cells. 



AlS was expected, starch was present in abundance, and 

 was easily seen even without the aid of iodine solution. 



Tannin was shown by ferric chloride solution, which 

 gave a color varying from deep green to black, according 

 to the quantity of the substance in the cell. Copper acetate, 

 in a saturated solution of which the threads were allowed 

 to remain for several days, gave a brown precipitate. 



If a vegetating cell be tested for a reducing sugar by 

 Fehling's solution there will be seen in the interior of the 

 cell one, or more generally two, areas over which the copper 

 oxide is deposited. These areas have the appearance of 

 contracted pellicles carrying the cuprous oxide in their 

 walls. They are situated inside the chlorophyll bands, and 

 if the test is properly carried out, the position of the bands 

 in the cell is not materially altered. 



The appearance and position of these structures indicate 

 that one of the innermost protoplasmic layers bounding 

 the vacuole of the cell carries in its substance the glucose. 

 By the prompt reaction of the Fehling's solution and the 

 glucose, the cuprous oxide was deposited where originally 

 the glucose existed. 



The most characteristic form for the pellicle to assume 

 is that of a flattened cone having the base directed toward 

 the end of the cell. One such cone is placed on either side 

 of the nucleus. In no other part of the cell can any 

 deposit of cuprous oxide be detected, though careless hand- 

 ling may cause these pellicles to break into a number of 

 pieces, when these will be found scattered over the cell. 

 Since only a small quantity of glucose is present in the 

 vegetating cell the pellicle bearing the copper deposit was 

 colored a light red-brown when viewed by transmitted 

 light. 



The microscope revealed the presence of two varieties of 



