340 Dr. F. Cohn on a new genus of the family of Volvocinete. 



concerning their structure and function ; they must not be re- 

 garded as cell-nuclei, although they resemble them very much, 

 especially when only one is present. Caustic potash, which de- 

 stroys the rest of the contents of the primordial-cells, makes the 

 chlorophyll-utricles of Stephanosphcera show themselves more 

 distinctly as hollow rings, surrounded by a membrane which is 

 rather granular; iodine colours them deep violet, which leads to 

 the conclvision of the presence of starch *. Ehrenberg thought 

 the chlorophyll-utricles were to be recognized as the testes of 

 the Volvocine(B ; it is certain, however, that these structures may 

 be seen in greater or less number, in exactly the same way, in 

 undeniable plants, such as Hydrodictyon, (Edogonium, Mougeotia 

 and others (vide, among others, H. von Mohl's Treatise on the 

 Vegetable Cell, in 11. Wagner's Handworterbuch der Physiol, pi. 1. 

 figs. 20-24, and in the English Translation ditto). 



I have already shown that the primordial-cells of Stephano- 

 sphara as well as those of Chlamydococcus are destitute of a spe- 

 cial rigid membrane ; consequently they do not correspond to 

 perfect cells, but on the whole only to primordial-utricles. In 

 like manner the curious colourless mucous filaments which ex- 

 tend out from the extremities of the primordial-cell of Stepha- 

 nosphcera, are evidently analogous to the rays which make one 

 condition of the Chlamydococcus-eelh look hairy (var. setiger, 

 V. Flotow). They are merely prolongations of the colourless 

 protoplasm forming the substance of the primordial- cells, and 

 correspond pretty well morphologically to the reticulated branch- 

 ing filaments of protoplasm, the sap- currents as they are termed, 

 which maintain the nucleus suspended freely in the interior of 

 the cells of the articulations of Spjirogrjra, or of the hairs of the 

 anthers of Tradescantia. Alcohol and acids cause these pro- 

 longations to be retracted into the substance of the primordial- 

 cells ; the same thing takes place during the course of the deve- 

 lopment. Ehrenberg has called these peculiar mucous rays, which 

 also occur in some other Volvocinea, in some cases a tail {Sj/n- 

 ura, Uroglcena), in others connecting canals or indications of a 

 vascular system (in Volvox and Gonium). These protoplasm- 

 filaments naturally present a different aspect according to tlie 

 shape and arrangement of the primordial-cells : while they ap- 

 pear as a wreath of cilia in the globular Chlaniydococcus-ceW, in 

 the more spindle-shaped Stephanosphcera they rather resemble 



* It is well known that the chlorophyll-utricles of most of the Algae, as 

 well as the analogous chlorophyll-globules occurring in the cells of almost 

 all Phanerogamia, secrete starch. Alex. Braun indeed lias called the corre- 

 sponding structures in CJilamydococcns pluvialis simply " Amylon-glo- 

 bules," in which may be detected an envelope and a nucleus (Verjungung, 

 222). 



