Premium
THE DENSITY OF UNICELLULAR ORGANISMS
Author(s) -
ALLISON R. V.
Publication year - 1924
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1924.tb05700.x
Subject(s) - biology , dry matter , cyst , zoology , volume (thermodynamics) , algae , ecology , thermodynamics , physics , medicine , radiology
SUMMARY.1 By measuring the rate of fall of certain unicellular organisms of known diameter under appropriate conditions, their density has been calculated by the formula of Stokes. 2 According to this method the average ansity of algal cells studied is 1.098 and that for the cysts of Gonostomum sp. 1.057. 3 The density of the algal cells was found to vary greatly between the larger and smaller sizes, while that for cells intermediate was fairly constant. In the case of protozoan cysts the total variations in average density was much less marked. 4 It was found that during maturation, the cysts of a certain species of Colpoda decreased to one fourth their original volume, while their average density increased from 1.04 to 1.06. 5 Since many of the 4‐day cysts of Colpoda sp. excysted during or shortly after the measurement of their density, the average density, 1.042, for this group is thought to represent quite accurately the density of the young animals in this early stage. 6 By the application of the formula of Hehner and Richmond to the density values so obtained, a tentative value has been derived for the actual dry matter of the cells studied. 7 It has been found by calculation upon this basis that the dry matter of the young cysts (4‐day) of Colpoda sp. amounts to 10.6 per cent. while at the later stage (20‐day) it is 15.1 per cent. 8 It appears that 64.3 per cent, of the total dry matter of the cyst and 76.2 per cent, of the water content are lost during maturation. With regard to the total percentage of loss in terms of either constituent, it has been found that water represents 90.9 per cent, and dry matter 9.1 per cent, of the total loss respectively.