. Plant studies; an elementary botany. Botany. THE GEEAT GEOUPS OF AUijK 233. together imix'dded in the jelly-like matrix formed by the wall material (Fig. 201). These imbedded groups of indi- viduals are spoken of as colonies, and as colonies become large they break up into new colonies, the individual cells composing them continuing to divide and form new individuals. This represents a very simple life his- tory, in fact a simjjler one could hard- ly be imagined. 160. Nostoc,âThese forms occur in Jelly-like masses in damp places. If the jelly be examined it will be found to contain imbedded
. Plant studies; an elementary botany. Botany. THE GEEAT GEOUPS OF AUijK 233. together imix'dded in the jelly-like matrix formed by the wall material (Fig. 201). These imbedded groups of indi- viduals are spoken of as colonies, and as colonies become large they break up into new colonies, the individual cells composing them continuing to divide and form new individuals. This represents a very simple life his- tory, in fact a simjjler one could hard- ly be imagined. 160. Nostoc,âThese forms occur in Jelly-like masses in damp places. If the jelly be examined it will be found to contain imbedded in it numerous cells like those of (rkeocapsie, but they are strung together to form chains of varying lengths (Fig. 202). The jelly in which these chains are imbedded is the same as that found in Glceoaqjsn, being formed l)y the cell walls becoming mucilaginous and swollen. One notable fact is that all the cells in the chain are not alike, for at irregu- lar intervals there oc- cur larger colorless cells, an illustration of the differentiation of cells. These larger cells are known as het- erocysts (Fig. 202, A), which simply means " other ; It is observed that when the chain breaks up Fig. 303. Ifostoe. a blue-green alga, showing the mto fragments Cach chain-like fllaments, and the heterocysts 1,1) fragment isCOmpOSed which determine the breaking up of the chain.â '"â n i , ,vELL. ot the cells between Fig. 201. Gkvocajisa, a tjliiL'-gi-een alga, show- ing single cells, and small groupg wliich have been formed by division and are held together by the enveloping muci- lage.â Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John Merle, 1851-1928. New York, D. Appleton and Company
Size: 1231px × 2030px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1900
