ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 333 



furrow a conjugation-tube. The two tubes unite and the cell-contents 

 pass into the tubes and there become fused and form a zygospore. 

 Such a method of sexual reproduction strongly supports the view of 

 the relationship of the Peridineas with the Conjugates and Diatoms. 



Siphonese Studies. * — A. Ernst publishes a continuation of these 

 studies, of which No. II. is entitled " Contributions to a knowledge of 

 Codiaceas." He begins by describing a plant from Posilipo as a new 

 species of Udotea, and calls it U. minima, comparing it with U. Des- 

 fontainii, the well-known Mediterranean species. It is characterised by 

 the absence of the peripheral filaments, which occur as a rule in U. 

 Desfontainii. A section of this paper is devoted to a consideration of 

 this latter species, and another to its regenerative power in connection 

 with external injury. This power it possesses to a considerable degree. 

 The " Phylogeny and System of Codiaceaa " forms the next subject, 

 and is followed by remarks on the genus Godium, which is placed by 

 the author with Pseudocodium in sub-family Codieas, as distinct from 

 sub-family Udoteae, in the family Codiaceas. The nine families of 

 Siphoneaa are enumerated, as also the four of Siphonocladeaj, and the 

 question of reproduction in this group is discussed. The author is 

 strongly of opinion that the so-called zoosporangia of Udotea, figured 

 in certain works, are merely foreign bodies, and have no connection 

 with the plant. He has often searched for sporangia on specimens of 

 Udotea, and has tried to grow plants of his new species with a view to 

 the development of fruit, but without success. He thinks it, however, 

 premature to assume that although in the past many of the genera of 

 Siphoneag may have had sexual reproductive organs, they are now 

 reduced to methods of vegetative propagation only. This conclusion 

 can only be reached after years of growth under inspection in native 

 habitats. The paper is illustrated by three plates. 



The third of the Siphoneaa studies is devoted to the morphology 

 and physiology of the reproductive cells of the genus Vaucheria. The 

 author begins by a chapter on the formation of sporangia and aplano- 

 spores in Vaucheria piloboloides Thur., in which he gives a short resumi 

 of work done on the zoospores of Vaucheria, and then goes on to 

 describe the asexual spores of V. piloboloides, which he considers occupy 

 an intermediate position between the zoospore of V. sessilis and the 

 aplanospore of V. geminata. The formation of both sporangium and 

 spore in V. piloboloides occupies only a few hours, and the process is 

 described in detail, as well as the subsequent escape of the spores. The 

 free spores of V. piloboloides are distinguished from those of any other 

 species of Vaucheria by their elongated club-shaped form, which is pre- 

 served even after germination. This process is also described. The 

 conditions of spore-formation in V. piloboloides are then discussed. In 

 contrast to the fresh- water species of Vaucheria, V. piloboloides develops 

 under conditions more or less stable, and the period of its vegetation 

 lasts at Naples about two months. Successful attempts were made to 

 grow it under observation, and the best methods are given for arousing 

 the formation of zoospores. Various experiments were tried in con- 



* Beih. Bot. CentralbL, xvi. (1904) pp. 199-236 (3 pte.); pp. 367-82 (1 pi.). 

 June 15th, 1904 2 A 



