ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 999 



Trichosolen ?, ApjoJmia, Struvea, Chamsedoris, Dictyosphsena, Anadyomene). 

 V. CAULERPEiE (Caulerpa). VI. Dasyclade^ (Dasycladus, Chlorocladus, 

 Botryophora, Cymopolia, Neomeris, Bornetella, Halicoryne, Polyphysa, Aceta- 

 bularia, Pleiophysaf). Uutler Avrainvillea are included Fradelia, Chloro- 

 plegma, and Bhipilia. CMorodictyon and Codiolum are altogether excluded. 

 The position of a number of these genera is provisional only, as in a 

 considerable proportion of them the fructification and mode of reproduction 

 are unknown, and for the same reason the delimitation of the families depends 

 on characters which have no permanent value. 



Growth of the Cell- wall and other phenomena in the Siphoneae.* — 

 In order to determine the question whether the growth of the cell-wall takes 

 place by aj)position or by intussusception, Herr F. Noll suggests the use of 

 staining reagents which shall colour the fully formed parts of the cell-wall, 

 while the parts in process of formation are left uncoloured. For this pur- 

 pose he employed Berlin blue or Turnbull's blue, and applied the test to 

 marine algae in which the cell-wall grows with great rapidity, viz. Caulerpa 

 prolifero, and species of Bryopsis and Derbesia. Having coloured the cell- 

 walls already formed in the way indicated, their growth was then continued 

 without further staining, when new colourless lamellae of the cell-wall were 

 found to be formed within those coloured blue, showing that the growth 

 takes place by apposition only. In the transparent tubes of Bryopsis and 

 Derbesia it was clearly seen that no increase of thickness took place by 

 intussusception, and the same was the case also with the apical growth. 



Herr Noll also investigated the function of the remarkable bands of 

 cellulose within the tube of Caulerpa, which have generally been supposed 

 to be for the purpose of strengthening. He found that they could have no 

 appreciable value for this purpose, but that they display an extraordinary 

 power of conduction in the direction of their length. Their object appears 

 to be to promote the rapid passage of oxygen and other substances to the 

 interior of the elongated cell, where they are required for respiration and 

 other purposes. 



The seat of the phenomena of heliotropism and geotropism displayed by 

 these algae was determined to be the parietal layer of protoplasm. In these 

 plants of low organization external forces have much more direct influence 

 than in higher plants, where morphological differentiation of organs for 

 special purposes has already taken place. 



Fresh-water Chsetomorphas.t — Herr G. Lagerheim describes a new 

 species of Chsetomorpha ((7. Herbipolensis^ from water in a conservatory at 

 Wiirzburg, and discusses also all the species of this genus that are brackish 

 or fresh-water in contrast with the larger number of marine species. 



Sensitiveness of Spirogyra to shock.| — Mr. S. Coulter records the 

 observation that if filaments of Spirogyra are cut through as carefully as 

 possible with the sharpest instrument, eight or ten cells nearest to the 

 laceration showed striking changes in their protoplasmic contents, the 

 spiral bands of chlorophyll being broken up and exhibiting a tendency for 

 the protoplasm to collect roimd certain definite centres. It was a note- 

 worthy fact that the pond from which the Spirogyra was taken contained 

 water which was always at a comparatively high temperature ; under 

 ordinary conditions the same sensitiveness was not displayed by the 

 Spirogyra. 



* Bot. Ztg., slv. (1887) pp. 473-82. 



t Ber. Deutsch. Bot. Gesell., v. (1887) pp. 195-202 (1 pi.). 



X Bot. Gazette, xii, (1887) pp. 153-7 (5 figs.)- 



