Olive, Mitotic divisioii of tlie iiuclei of tlie Cyauopliyceae. 37 



Glopocapsa, however, furnislies two peciiliarities in its cell 

 division. Tlie cutting in two of the cell is accomplished l)y 

 simple constriction, instead of by a ring-formed wall; and, 

 secondly, it lias an exceptional plane of division whicli lias been, 

 so far as the writer is aware, nowliere eise observed. Instead 

 of the division of the cell occurring in a plane parallel to that 

 of nuclear hssion, as in normal cases, in Gloeocap.s'a^ the plane 

 of constriction is at right angles to that of the division of tlic 

 nucleus (p. 30). 



11. Although the central body in vegetative tilaments seems 

 to be in a state of continuoiis mitotic activity it appears occa- 

 sionally to make a beginning toward a resting condition, and 

 to form a delicate membrane and karyolympli. It is probable, 

 however, that the nuclei in the active filaments do not ordinarily 

 approach nearer to a state of rest than the spireme condition 

 or a stage immediately prior to it. This condition is not nsu- 

 ally attended by the secretion of karyolympli (p. 32). 



12. In spores and heterocysts, on the otlier liand, the 

 nuclei enter a condition of rest, in which nuclear vacuole and 

 membrane are formed. In heterocysts, the protoplasmic Con- 

 tents soon die, leaving nothing finally evident but disorganized 

 chromatin granulös. 



In some spores, the nuclear vacuole and membrane may 

 persist; whereas, in the case of Cylinflrospermum and probably 

 in otlier forms, the multitude of granulös of reserve food en- 

 croach so upon the nuclear cavit}^ that, in the niature spores, 

 the membrane appears finally to be broken down and the gra- 

 nulös enter the nuclear space. We thus have the peculiar 

 phenomenon of an enormous central body, eontaining an abun- 

 dance of cyanopliycin bodies, in the interstices of which are 

 the chromatin granulös (pp. 27 — 29). 



13. The blue and green coloring matters are held in a dif- 

 fused State in a peripheral chromatophore, which may have, in 

 some species, the form of a hollow cy linder, or, in otliers, of 

 a hollow sphere. In the six genera examined, no evidence 

 whatever was found of the presence of iiiinute „cyanoplastids" 

 (pp. 14-16). 



14. The only kinds of granulär inclusions which were found 

 were the cyanopliycin granulös and the slinie globules. The 

 cyano])liycin granules are evidontly a form of stored food; and. 

 in tliose algae with a cylindrical chromatophore, they lie in the 

 cytoplasm, generally closely packed along both sides of tlie 

 cross partitions. In tliose .species with a hollow sjDherical chrom- 

 atophore, the cyano])hycin bodies appear to be located in the 

 chromatophore itself, or, more probably, in the cytoplasm be- 

 tween the cliromatoplior(! and the central body (p. 33). 



The slime globules are also, at least as a usual thing, lo- 

 cated in the cytoplasm. They lie, however, in the immediate 

 vicinity of the nucleus; so close are they, in fact, that they 



