84 INTRODUCTION TO CYTOLOGY 



The number of chondriosomes present varies greatly with the tissue 

 and the degree of its differentiation. They are usually abundant in 

 young or active cells and relatively few or even absent in fully differ- 

 entiated ones. In living cells, moreover, they can be seen constantly 

 appearing and disappearing. The arrangement of the chondriosomes 

 within the cell varies; this is often clearly related to certain functional 

 activities, as in certain polarized gland cells. ^ In pathological animal 

 tissues they show pronounced qualitative and quantitative changes, of 

 which one of the most characteristic is the breaking up of filaments into 

 granules (see E. V. Cowdry, 1924a6). 



Physical and Chemical Nature. — Chondriosomes have a semifluid 

 consistency. Under either bright- or dark-field illumination they appear 

 homogeneous (Guilliermond, 1929c). It is reported that they are doubly 

 refractive by polarized light (Giroud, 1928). When the cytoplasm is not 

 too viscous they may be centrifuged out, which shows that their specific 

 gravity exceeds that of the cytoplasm (Faure-Fremiet, 1913). In both 

 plants and animals they melt at a temperature of 48° to 50°C.'^ In 

 hypotonic solutions they become swollen and vesicular, whereas in hyper- 

 tonic media they shrink and become slender. In animal cells Rum- 

 jantzew (1926), studying the effect of variations in the pH of the medium, 

 observed that they remained unchanged between 6 and 8, broke up or 

 agglutinated between 5.8 and 3, and formed networks and finally dis- 

 solved as the pH was raised to 10. Lewis and Lewis (1924) observed 

 filamentous ones become vesicular at 4.4 and shorten into granules at 

 9.6. As would be expected, many fixing reagents bring about decided 

 alterations in their form,^ while those with much acetic acid destroy them 

 altogether. They are well preserved by formalin and potassium bichro- 

 mate, provided the solutions are not too acidic. 



Chemical studies, though incomplete, indicate that chondriosomes are 

 composed of phospholipides and albumins.^ Besides staining with 

 hsematoxylin and several other dyes commonly employed with fixed 

 material, they show a characteristic affinity for certain intra-vitam 

 stains, notably Janus green. According to E. V. Cowdry (1916), chon- 

 driosomes may be provisionally defined as "substances which occur in 

 the form of granules, rods, and filaments in almost all living cells, which 

 react positively to Janus green and which, by their solubilities and stain- 

 ing reactions, resemble phospholipins and, to a lesser extent, albumins. " 



Origin and Multiplication. — The question of the origin and multiplica- 

 tion of chondriosomes has been much debated. Evidence for their 



^Bensley (1916), E. V. Cowdry (1918). 

 'Policard (1912), N. H. Cowdry (1917). 

 sSchaxel (1911c), Kiugery (1917). 



3 Regaud (1908), Faurc-Fremiet (1910a), Lowschin (1913), Lewitsky (1924), 

 Giroud (1925a6, 1929), Milovidov (1928c). 



