648 SUMMARY OF CURRENT RESEARCHES RELATING TO 



As to tlie preservation of clesmids, Mr. Maskell has found no fluid 

 which is entirely satisfactory, but, " taking them all round, he believes 

 that of all preservative fluids glycerine is the best." 



Division of Closterium intermedium.* — J. Schaarschmidt de- 

 scribes the mode of division in this desmid, which is similar to that 

 of Penium interruptum. The cell has a primary suture, and a secondary 

 suture in the middle of each hemicyst. Beneath these are formed the 

 new cell-nuclei, which are in all probability daughter-nuclei of that 

 of the mother-cell. The cell-wall of the mother-cell then ruptures 

 along the primary suture ; the daughter-cells rapidly attain their full 

 size and separate from one another. The secondary sutures are ana- 

 logous structures to the " caps" of (Edogonium. Before each division 

 the cuticle is raised from the cell-wall in the form of a hollow ring, 

 which ruptures when the division takes place, while the very plastic 

 cell-wall extends rapidly. The number of secondary and tertiary 

 sutures may be very large, up to twenty-four, indicating the number 

 of times that the individual has divided. The author is of opinion 

 that all the species of Closterium with secondary sutures divide in this 

 way, as well as in the ordinary way. 



Schmidt's Atlas of the Diatomacese. — We understand that the 

 publication of this work is to be resumed, and that two further parts 

 are just ready for issue. The other four will, it is hoped, appear in 

 October. 



Van Heurck's Synopsis of Belgian DiatomaceaB. — Part III. of 



this workf is now published, containing the first portion of the 

 Pseudo-Eaphidese (plates 31-33). 



Delogne's Belgian Diatoms. — M. C. H. Delogne, assistant naturalist 

 of the State Botanical Garden at Brussels, is issuing a series of 

 preparations of Belgian diatoms. The nomenclature adopted is that 

 of Van Heurck's ' Synopsis,' and that author has revised M. Delogne's 

 determinations, or identified the forms by the types of his own collec- 

 tion. They are " enclosed in an elegant and solid box, having the 

 appearance of a book, and can be placed on the library shelves."| 



Peculiar Structure of Isthmia enervis. — Mr. W. S. Kent records § 

 a remarkable internal structure in the unicellular frustules of this 

 marine diatom, examined in the living state. The characteristic 

 olive-brown cell-contents, or endochrome, was found to be collected 

 for the most part into a more or less extensive central spheroidal mass, 

 from which radiating and frequently branched granular, thread-like 

 prolongations of the same substance extended to and united with the 

 periphery. Submitted to high magnifying power (700 diameters), 

 both the central mass of endochrome and its radiating prolongations 

 were shown to be composed of an aggregation of minute brown, ovate 



* Magy. novenytani lapok, v. (1881) pp. 3-6. See Boi Centralbl., vi. (1881) 

 p.l. 



t See this Journal, iii. (1880) p. 687. 



X Cf. Brehissoniii, iii. (ISSl) pp. ir)(;-7. 



§ Kent's 'Manual of tlic Infusoria,' i. (1880) p. 59. 



