ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 65 



account of the fertilisation' and of the resulting oospore. Attempts to 

 follow the germination of the latter have so far been unsuccessful. 

 Besides the sexual method of reproduction, there exists in Dichotomo- 

 siphon an asexual form of reproduction which is unlike anything known 

 till now among the Siphone*. Unbranched, rhizoid-like filaments 

 arise on the plant, and these bear tubercles, which become thick in 

 protoplasm, and germinate after being cut off by a transverse wall from 

 the rhizoid-like filament. 



As regards the systematic position, the author places this genus 

 nearest to Vaucheria, from which, however, it has many points of dif- 

 ference. A striking resemblance exists in certain points to Halimeda 

 and Codium, but especially to a still undescribed, young condition of 

 Udotea. A full diagnosis, followed by references to literature, closes this 

 paper. The various conditions described are figured in coloured plates. 



Cell-Membrane of Desmidiaceae.* — J. Lutkemiiller has made an 

 exhaustive study of this subject, and now publishes the result of his 

 nine years' work. Several hundred species were examined, and the 

 author is enabled to divide the family into five groups of genera, which 

 are sharply distinguished from one another by constant anatomical and 

 physiological characteristics. The types of the five groups are Cosmarium, 

 Olosterium, Penium, Gonatozygon, and Sjjirotcenia. The cell-membrane, 

 pore-apparatus, and cell-division of the various types are dealt with, 

 and remarks are made on the position of the genus Penium, relationship 

 of the types, function of the pore-apparatus, and systematic treatment. 

 Finally a synopsis of genera in Desmidiaceae is given, drawn up on the 

 lines of classification propounded by the author. 



Ulotrichaceae and Chsetophoracese of the United States.f — T. E. 

 Hazen publishes the result of five years 1 study on these groups of alga?. 

 After giving short accounts of his method of study and methods of 

 preservation, he gives some remarks on their distribution, which, he 

 says, is still somewhat doubtful from the unreliability of so many 

 records. Then follows the systematic treatment of the two groups, in 

 which the author gives diagnoses of the families and genera, with keys 

 to genera and species. After the name of each species are given 

 synopses and references to literature, a diagnosis, references to Exsiccata:, 

 habitats and distribution, and finally critical notes. Ten new species 

 are described, and three new forms or varieties. The author has en- 

 deavoured to emphasise cytological, and especially chromatophore cha- 

 racters as much as possible, but in many cases he has been reluctantly 

 compelled to fall back on the character of cell-measurements "to 

 separate species which, after careful observation, he is convinced are 

 distinct." A list of bibliography and an index complete this paper. 



(Edogonium.J — F. E. Fritsch has made a detailed study of the 

 young root-ends of five species of this genus, and comes to the conclu- 

 sion that certain types are characteristic of certain species. It is gene- 

 rally found that the form of the root-end varies, according to whether 



* Beitr. z. Biol. d. PflHtizon, viii. (1902) pp. 347-414 (3 pis.). 

 t Mem. Torr. Bot. Club, xi. (1902) pp. 135-250 (23 pis.)- 

 % Ann. Bot., xvi. (1902) [.p. 467-85 (3 figs, in text). 



Feb. 18th, 1908 f 



