Beer, Development of the xiolleu grain and anther of some Onagraceae. 305 



Tlie comparison whicli Meves has drawn between these 

 deeply staining fibres of the tapetal cytoplasm and the chon- 

 dromiten of certain animal celLs is of the highest interest. 



In a large number of actively functional cells, belonging to 

 the most various tissues of the animal body, chromatic structures 

 have been found in the cytoplasm und described. under the 

 names of mitochondrien, chondromiten, pseudochromosomes, yolk- 

 nuclei, chromidien, apparato reticolare etc. 



GoldschmidtM has recently found good grounds for grou- 

 ping all these structures together and he has shown by direct 

 experiment that at least in some cases (e. g. muscle-cells of 

 Äscaris lumbricoides) ihey are directly connected with the functional 

 activity of the cell. 



In the tapetum the fibres (or their derivatives) unquestio- 

 nably play a prominent part in the cytoplasmic growth of the 

 pollen-protoplasts and no doubt in the animal cell they are also in 

 some way associated with the elaboration of complex organic 

 substances."^) In tliis relation it may be recalled that several 

 physiological chemists have pointed out the probability of 

 nuclein or one of its constituent molecular groups forming a 

 centre or starting point for the synthesis of complex organic 

 matters in the living cell. 



The origen and chemical nature of these chromidial struc- 

 tures has, however, not yet been satisfactorily determined in all 

 cases. In some cells which have been studied by Gold- 

 schmidt it is highly probable that they are derived from the 

 chromatin of the nucleus. 



I have shown above that the fibres in the tapetal cells of 

 Oenothera possess a nuclear origen and may be referred to the 

 transformation of the nucleoli and nuclear membranes. 



The staining reactions and the behaviour of these nucleoli, 

 whilst the nucleus is still intact, show that they are, at least 

 partly, composed of chromatin whilst the nuclear wall also seems 

 to owe its affinity for nuclear dyes to the deposition of finely 

 granulär chromatin upon its inner face or witliin its sub- 

 stance. 



We see therefore that the fibres lying in the tapetal cyto- 

 plasm are to a great extent derived from the chromatin of the 

 nucleus and that mucli of the substance that ultimately passes 

 into the pollen grains is a derivative of chromatin. 



The walls of the tapetum, during the greater part of the 

 development of the anther are of a somewhat mucilaginous 

 nature and can be very distinctly differentiated by means of 

 an alkaline Solution of congo red. In the older anther these 



ij Goldsclimidt, E. „Der Chromidialapparat lebhaft funktionierender 

 Gewebzellen". (Zoolog. Jahrb. Abt. f. Anat. u. Ontogenie d. Tiere. Bd. XXI. 

 1904. p. p. 1—100.) 



-) For exaniple note the rehition which Mathews fonnd to exist bet- 

 ween the deeply staining iibres and tlie Zymogen granules of certain pan- 

 creas and liver cells. (Journ. Morphol. XV. 8uppl. 1899.) 



