ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 5G3" 



Godium tomcntosim, which he makes the type of a new genus, and names 

 Ceramothamnion Codii g. et sp. n. The following is the diagnosis of 

 the genus : — Plant consisting of prostrate filaments giving rise above 

 to erect filaments and below to rhizoids. Erect and prostrate filaments 

 alike in structure, monosiphonous throughout, with small cells collected 

 at the nodes; growing tip straight, never circinate ; chromatophores 

 rhodophyceous, in elongated bauds running almost the length of the 

 internodal cells ; antherids, tetraspores, and polyspores present ; tetra- 

 sporanges borne at nodes, cruciate, provided with enveloping sterile 

 cells, proliferating by successive formation of new tetrasporanges inside 

 the old ones. The proliferation of the tetrasporanges is a special 

 feature of the genus. 



Tetrasporange of Polysiphonia.* — F. Heydrich has followed out in 

 detail the fertilisation of the tetrasporange in Polysiphonia violacea. 

 The sporange- segment consists, at a certain period, of ten cells, — a 

 central cell, four long pericentral cells, two short pericentral cells, a 

 tetrasporange mother-cell (protospore), a stalk-cell, and a wedge-shaped 

 lateral cell. The contents of these cells are described in detail, as well 

 as the pitting of the cell-walls through which the protoplasmic con- 

 nections take place. The mother-cell of the tetrasporange appears to 

 have no true pitting. The young tetrasporange consists, at the outset, 

 of two free cells. A true union or fusion appears to take place between 

 the protospore and the stalk-cell, resulting in the production of tetra- 

 nuclei or tetraspore nuclei. 



The author's observations appear to confirm the suspicion of some 

 previous observers that the tetraspores, at least of Polysiphonia, are of 

 sexual origin. 



Chambers and Pores in the Cell-wall of Diatoms.f — 0. Miiller 

 continues his investigation of this subject, especially in the species 

 Stephanopjyxis Palmeriana, Sceletonema costatum, Lauderia annulata, 

 Eupodiscus Argus, and Triceratium favus. He finds treatment with 

 hot solution of sodium carbonate or of potassium hydrate useful in 

 studying the structure of the cell-wall. 



In Stephanopyxis Palmeriana he has determined that the spines 

 which connect the cells with one another are tubes, to which are at- 

 tached three or four delicate rings arranged spirally. Their purpose 

 is evidently to assist in the connection of the protoplasm of the indi- 

 vidual cells. The same probably occurs in many other diatoms, among 

 which Melosira granulata may be specially mentioned. 



In Sceletonema costatum and Lauderia annulata a similar connection 

 between the protoplasm of adjoining cells occurs, without which the 

 division of the free superficial protoplasm could not take place. The 

 formation of the tubes is probably effected by direct excretion from the 

 threads of protoplasm. The same is the case with the canals of Tricera- 

 tium favus, with subsequent production of the wing-like appendages,, 

 as in Stephanopyxis. 



* Ber. Deutsch. Bot. Ges., xix. (1901) pp. 55-71 (1 pi.). 



t Tom. cit., pp. 195-210 (1 pi. and 3 figs ). Cf. this Journal, ante, p. 306. 



