Vol. 2] Gardner. — Cytological Studies in Cyanophyceae. 275 



The ordinary microchemical tests did not yield definite and con- 

 clusive results to the writer. In order to test the matter further, 

 the method of extracting glycogen from animal tissue was re- 

 sorted to. Mercuric chloride and Esbach's reagent were used to 

 precipitate proteids in macerated rabbit's liver, after which the 

 glycogen was precipitated with alcohol. This was done to test 

 the reagents and to secure glycogen for comparison. A quantity 

 of Oscillatoria was then rubbed up in the same way with some of 

 these same solutions, and filtered. The filtrate was then treated 

 with alcohol, and a precipitate was thrown down which had the 

 same appearance as the glycogen prepared from the rabbit's 

 liver, and which gave all of the characteristic glycogen reactions. 

 From this result it seems just to conclude that glycogen is pro- 

 duced in the Cyanophyceae. 



Before making this test for glycogen, I was of the opinion 

 that it is not to be found in this group of organisms, but that 

 sugar is the first product of assimilation, and that the excess is 

 stored in this form. I came to this conclusion because aqueous 

 extracts of a variety of forms of Cyanophyceae pulverized with 

 fine sand in a mortar always readily reduced Fehling's solution. 



It is of course possible that this reducing body is something- 

 else than sugar; but, since glycogen is produced in the animal 

 body from sugar, it is quite probable that the first product of 

 assimilation in the Cyanophyceae is sugar, and that some of this 

 is converted into glycogen and stored in this form. 



V. EXPEEIMENTAL CULTURES. 



I have already mentioned that the Cyanophyceae as a group 

 have persisted doubtless from very ancient time, because of their 

 power of adaptability to changes of environment without much 

 modification in form. There is scarcely a habitat to which some 

 species has not adapted itself, and in many cases the same species 

 is capable of withstanding extremes in heat, moisture, and air 

 supply. 



Several writers on the group have stated that change in habi- 

 tat, even though slight, results in profound changes in cytolog- 

 ical characters. The writer has made some observations and per- 



