ON THE INVEStlGATION OF CYANOt'HYCEiG. ^^19 



Investigation of the Giianophijcea'. — Report of the Committee, cu7isist- 

 inq of Professor J. B. Farmer (Ghairvian), Dr. F. F. Blackman 

 (Secretarn), Professor Marshall' Ward, Mr. Walter C4ardiner, 

 ami Dr. I). H. Scott. {Drairn up hij the Secretary.) 



This investigation has been continued by Mr. Harold Wager, and is now 

 practically completed. A preliminary paper has been published in the 

 « Proceedings of the Royal Society.' The following is given by Mr. Wager 

 as a brief summary of the principal results arrived at :— 



'The cell contents are divided into two distinct regions t (1) an 

 outer peripheral layer in which the colouring matters are contained, and 

 (2) a central portion which is colourless. Both exhibit a reticulate or 

 alveolate structure, and contain granules of varying sizes. Under certain 

 conditions glycogen is present in the cell, often in considerable quan- 

 tities, 



• The colouring matters, chlorophyll, Ac, are contained in small granules 

 embedded in the reticulate network of the cytoplasm. They often appear 

 to be arranged in regular rows, which give the impression of coloured 

 granular fibrils. It is probable that these granules are comparable to the 

 " grana " of ordinary chloroplasts, and not actually to the chloroplasts 

 themselves. 



' The central body contains chromatin in the form of minute granules, 

 more or less fused together on a network. This network is not sharply 

 marked off from the peripheral cytoplasm, but it appears to be contained 

 in a vacuole, and at certain times the limiting layer of the vacuole is 

 visible. The central body varies much at different times in the amount 

 of chromatin that it contains. It is more abundant in actively growing 

 healthy cells, in which constant cell division is going on ; in such cells a 

 very pronounced and distinct reaction for phosphorus is given when 

 treated according to the methods of Macallum. 



' There seems to be no reasonable doubt that this central body corre- 

 sponds to the nucleus of the higher plants. It is not precisely similar in 

 structure and appearance, but the presence of chromatin, the network- 

 like structure, and the fact that it is contained in a vacuole and is sharply 

 differentiated by reagents from the surrounding cytoplasm sufficiently in- 

 dicate its nuclear character. We are therefore justified in speaking of 

 it as a nucleus. In the process of division the nucleus simulates in a 

 remarkable manner certain features of the mitotic division of higher 

 plants, but a very careful examination of the whole process in various 

 species of Cyanophyceas convinces me that it is rather a case of direct 

 division, and not a true mitotic division. Nevertheless it may be justifiable 

 to regard it as a rudimentary form of indirect division. As the cell 

 wrows in length the nuclear network becomes drawn out in a longitudinal 

 direction, whilst tlie chromatin substance appears to become more abun- 

 dant. The result is in some cases an appearance as of numerous elongate 

 chromosomes lying side by side. The nucleus then becomes constricted 

 in the middle, and divides transversely into two daughter nuclei. At the 

 same time the new transverse cell wall is formed. Tlie formation of the 

 new cell walls appears, however, not to be dependent entirely upon the 



