1903.] The Cell Structure of the Cyanophycece.. 401 



s 'The Cell Structure of the Cyanophycese. Preliminary Paper." 

 By HAKOLD WAGER. Communicated by D. H. SCOTT, M.A., 

 Ph.D., F.E.S. Received October 9, 1903. 



The Cyanophycese form a group of plants which resemble the Algse 

 in some respects, but are sharply differentiated from them as regards 

 the structure of their cell contents. During the last 20 years they 

 have been the subject of numerous memoirs in which the problem 

 of their cell structure has been attacked, but with very varying 

 results, and much controversy has arisen concerning the exact nature 

 of the central body or nucleus and the presence or absence of a 

 chromatophore. On the one side, we have observers who deny the 

 existence of a nucleus or chromatophore in these forms, on the other, 

 those who consider that the central body is either a true nucleus or 

 the representative of one, and that the colouring matter is contained 

 in a definite chromatophore. 



The investigation of the cytology of these organisms is certainly not 

 an easy one, and it is not astonishing that so many different interpre- 

 tations are given of the facts observed. But it seems to me that 

 it is not an impossible task to arrive at more definite conclusions than 

 has hitherto been done, although we need to know far more of the 

 cytology of the lower organisms, both plant and animal, before we 

 can determine with any certainty the exact nature of their cell 

 structures or their relationship to other groups. 



In attacking the problem it is necessary that the methods used 

 should be as refined as apparatus and re-agents will allow, and it is 

 especially important not only that the highest possible powers of the 

 microscope should be used, but that the illumination should be as 

 perfect as possible. For this purpose a good sub-stage condenser is 

 necessary, and for the finer details of structure an oil immersion con- 

 denser has often been used. It is necessary also, in order to obtain 

 good comparable results, that the species investigated should be in 

 a sound and healthy state of development. The cells very soon 

 become altered in character if kept under unfavourable conditions, 

 and many of the contradictory accounts which have been given are 

 probably due, in part, to want of care in this respect. 



As regards the preservation and staining of these plants, the 

 ordinary methods used in connection with cytological investigations 

 are sufficient, but special care is required in their application, especially 

 in the matter of staining and washing out. For fixing and preserving 

 the material I have found corrosive sublimate, Flemming's chrom- 

 osmium-acetic solution, Pereny's fixing fluid, Gram's solution of iodine 

 and absolute alcohol the most useful. The various stains used included 



VOJ,, LXXII. 2 V 



