28 Olive, Mitotif divisicm of the nuclei of tlie Cyauophyceae. 



graniües seem to be in tlie cytoplasm, and to lie outside the 

 bluisli, irregiilarly defined central body. In fig. 94, wliicli sliows 

 a fully matured spore of the same species, similarly stained with 

 methylene bhie, the dense onter cytoplasmic zone seems, on the 

 contrary, to be free from granulös, wliicli now appear wholly 

 within the central portion. Fig. 93, stained with iron haematox- 

 ylin and eosin, is a longitudinal section of a very young 

 spore, in which the cyanophycin granules are stained red, and 

 are seen to be located only in the cytoplasm. Fig. 100 is a 

 cross section of a half matured spore, showing large and abun- 

 dant red granules, also in the cytoplasm alone. Figs. 101 — 103 

 are cross sections of young spores, all stained with Flemming's 

 triple stain, and all showing a well defined resting nucleus; 

 wliile figs. 96, 97, and 99 are similar sections of old spores, 

 similarly stained. Finally, fig. 95, a median longitudinal section 

 of a mature spore, should be noted. A careful comparison of 

 these figures leads us irresistibly to the conclusion that while, 

 in the young spores, the nucleus appears to begin to enter upon 

 a normal resting state, in the older spores, the abundant cyano- 

 phycin granules liave encroached so upon the middle, sap-fiUed, 

 nuclear cavity, that tliey are finally forced into it and fill the 

 nuclear space. Figs. 96, 97, and 99 all show clearly the un- 

 stained, globular Spaces in w^liich lie the cyanophycin granules, 

 some of which in the tAvo latter figures are located still in the 

 cytoplasm and others within the nucleus. In figs. 95 and 96, 

 all the food granules appear to lie within the limits of the 

 nucleus. In the preparations from which these latter drawings 

 w^ere made, the chromatin is stained dark reddish or purplish, 

 so that there can be no mistake as to the identity of the minute 

 nuclear granules which are seen in the interstices between the 

 unstained cyanophycin bodies. 



A possible explanation of tliis peculiar phenomenon seen in 

 the spore of Cylijulrospennum is afforded by the density of the 

 peripheral protoplasm, although this is a point of which I liave 

 not yet convinced myself. As the cyanophycin granules accu- 

 mulate in the cytoplasm in the imniediate neighborhood of the 

 nucleus, they finally become so abundant that they are probably 

 forced, on account of their increasing numbers as well as on 

 account of the density of the protoplasm in which they lie, 

 into the nuclear cavity. They tlius break down the delicate, 

 forming membrane, push in among the chromatin granules, and 

 in this way, in the mature spore, present the cuiious appearance 

 of an enormous central body, which is completely filled with 

 reserve food granules. "We can see, moreover, in figs. 95 — 99, 

 that the cyanphycin occupies only the outer portion of the 

 central body, while the middle is filled with a poorly defined, 

 aehromatic substance, in which are imbedded chromatin granules. 



Such a peculiar encroachment upon nuclear space has certain 

 resemblances to the phenomena seen in the spores of No-stoc 

 (figs. 59, 60j, in which the nuclei appear to be pres.sed into 



