76 SUMMARY OF CUJiRENT RESEARCHES RELATING TO 



of the number of chroiDosomes, but also in that it brings about new- 

 combinations of chromosomes in the daus^hter-nuclei, which in the 

 somatic equal division cannot take place. The reductions-division plays 

 as important a part in the new combination of chromosomes in the 

 nucleus as fertilization itself, and may be regarded as its final act. By 

 the reductions-division there is formed as great a possibility for new 

 combinations of chromosomes inside the nucleus, as by the fertilization 

 itself a possibility is given of new combinations of nuclei, and thereby of 



. the number of chromosomes. In Floridea3, which are treated in special 

 detail by the author, reductions-division takes place in the tetraspore 

 formation. Here the life of the diploid generation divides into two 

 different phases : the first, the gonimoblast phase in the cystocarp, in 

 intimate connexion with the gametophyte, as in the moss-sporogonium ; 

 the second, the tetraspore-forming phase, which takes its origin from the 

 germinating carpospore and arises here as an independent form of life, 

 entirely resembling externally the gametophyte. Floridea3, on the ftther 

 hand, which do not produce tetraspores have a reductions-division which 



• follows immediately on fertilization ; and the monospores which are pro- 

 duced by this type are purely germinating cells, and are not an integral 

 part of the alternation of generations. These two types of reduction 

 show also this difference— in the latter type only one sort of individual i» 

 produced, namely monoecious or dioecious sexual individuals with or 

 without monospores ; while the former type produces two sorts of indivi- 

 duals, sexual (monoecious or dioecious) and asexual (tetrasporic). The 

 former type is called by the author the haplohionik, the latter the diplo- 

 hiontic. He regards the haplobiontic as the original, from which the 

 diplobiontic has sprung, by the delay for some reason of the reductions- 

 division. 



Oceanic Algology.* — A. Mazza continues his description of types of 

 oceanic alg^. ' Completing his account of the non-articulate Corallineae 

 by a description of the structure of Masiophora, he passes on to a con- 

 sideration of the articulate Corallinese, describing Amphiroa and five of 

 its species; together with four varieties of A. tuberculosa, also Metagonio- 

 lithon with three of its species. 



Algae of Bermuda.!— F. S. Collins and A. B. Hervey publish a 

 Flora of the Algae of Bermuda, omitting the families Pihizophyllidaeea?, 

 Squamariaceae and Corallinacea?. In the introduction they discuss the 

 geological formation of the small group of islands, refer to previous 

 published work on the algs, and give a comparison of the flora with that 

 of nine of the best known regions where a similarity might be expected. 

 This is drawn up in tabular form, but is not intended to be in any way 

 exhaustive, owing to the impossibility of producing a complete com- 

 parison at this time of world-wide chaos. A list of important stations 

 is then given, with an indication of the characters of each, for the use of 

 future collectors. Concise keys have been drawn up for all the species 

 in a genus, aud a number of new species are described and figured. In 



* La Nuova Notarisia, xxix. (1918) pp. 1-34. 



t Proc. Amer. Acad. Arts and Sci., liii. No. 1 (1917) 195 pp. (6 pis.). 



