(^ 1 i V e, Älitotic divisiou of the iiuclei of tlie C'vauophyceae. 43 



Fig. 5G. Showiiig cyanopliyc-in granules only. staiiied witli safraniii. 



Fig. 57. A cross section. sliowiag in tlic central body both chroinatiii and- 



achromatin. 

 Fig. 58. A spore (?) wliicli shows a nucleus in i-esting condition. 

 Fig. 59. Another spore. showing about 8 cliromatin graniiles. Flem. 

 Fig. 60. A siniilar ])reparation. 



(Figs. 61—76. Gloeoeapm poli/dermatica Kütziug, all stained with He id. 



Fig. 61. A dividing cell, witli its snrrounding gelatinous wall. The central 

 body is too deeply stained. 



Fig. 62. A yonng cell, showing about 8 chroniatiii graniiles and the 

 achromatie portion. 



Fig. 63. A dividing cell, showing a deeply stained epireme thread. In the 

 vacnolar Spaces in the cytoplasm, are the ..slime globales" (of 

 Schmitz). 



Fig. 64. A young cell, in which the central body shows clearly 8 cliromatin 

 grannies and an achromatie portion. 



Fig. 65. A cell, apparently in a siniilar condition to that shown in fig. 64. 



Fig. 66. Shows aboiit 8 cliromatin graniiles, and at one side of the central 

 body, a large globiile. It is possible that such globular bodies are 

 slime globules: although they do not seem to be stained as the slime 

 in OsctUatoria and in otlier instances with methylene blue. 



Fig. 67. An older cell in which about 11 or 12 cliromatin graniiles are 

 shown. 



Fig. 68. A spireme stage, in which the simple spireme thread has a dis- 

 tinctlj^ Spiral form. 



Fig. 69. A young cell, showing only about 7 cliromatin graniiles. Certain 

 iibrous projections froni the central body, which extend into the cyto- 

 plasm between the food graniiles, are soniewhat stained by the haenia- 

 toxj^lin. 



Fig. 70. A cell in a state of division in which the spireme thread is double. 

 We can now couiit about 16 chromatin graniiles. 



Fig. 71. Showing the peculiar maniier in which the divided spiremes sepa- 

 rate, the one being drawn into the upper daiighter cell, the otlier 

 into the lower. It is possible that there are cytoplasmic fibers, corre- 

 si)onding to the mantle fibers, attaching the spireme to the end of 

 the cell, and exerting a pull as the cell elongates. These are not 

 evident, however. Judging from the figiire, there appears to be 

 an actual flowing of the spireme substance into the daiighter ceU. 

 The central spindle between the separating spiremes is obviously very 

 little developed. 



Fig. 72. A Spiral spireme thread in which we can count about 7 or 8 

 clu'omatin graniiles. 



Fig. 73. A constricting cell in which the two daughtei" spiremes have com- 

 pletely separated. Abont 8 chromatin graniiles can be counted in 

 eacli daiighter cell. 



Fig. 74. A spii'eme which appears to be spHttin<;' at the two ends. 



Fig. 75. Another instance, in which the Splitting of the spireme at the 

 two ends is even more obvious. 



Fig. 76. A Step further advauced than in iig. 73. in which the constrictiou 

 plane has completelv divided the cells. which have yet bccomo roun- 

 ded off. 



(Figs. 77 — 103, Cyliiulros/jcn/iiiiii shiijjKilc Boriict and Flahauit.) 



Fig. 77. A preparation freshly stained willi methylene blue. The heterocyst 

 show two miniite. dark blue slime globules; the spore, one (sometimes 

 -several); the vegetative cells each one to several. The granulation 

 in the cytoplasni of the spore is here qiiite evident. 



Fi.U'. 78. A lilunient. simihirly stained. in which the spore cell is no lar<;er 

 than the vegetative cells. The heterocyst bears at its end several 

 bacteria-like bodies. 



