372 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Spores on Sexual Plants of Nitophyllum punctatum.* — N. 

 Svedelius writes on a specimen of Nitophyllum punctatum, which is 

 interesting in connexion with his own and Yamanouchi's investigations 

 as to alternation of generations in Florideas. On the material in 

 question he found non-sexual spores growing on the same plant as the 

 cystocarps, and from their respective positions he considers it clear that 

 a distinct correlation exists between cystocarps and spores. They arise 

 always in proximity to each other, but if the cystocarps develop the 

 asexual spores are not formed completely ; if the trichogynes remain 

 unfertilized the asexual spores develop. An examination of the asexual 

 spores shows that they agree absolutely in their histological development 

 with normal tetraspores. They also behave like those bodies in forming 

 a number of nuclei, of which all but one degenerate in the course of 

 development. In spite of the material having been unsatisfactorily 

 fixed, the author was able to determine that no reduction by division 

 takes place. The spore remains undivided, has one nucleus and consti- 

 tutes a monospore. It has the same number of chromosomes as a 

 tetraspore. The author concludes, after examining the cystocarps, that 

 the plant in question is a haploicl female plant with normal cystocarp 

 development and fertilization, and the spore formation occurring on a 

 female plant takes place without reduction by division. Tbe spores are 

 therefore haploid monospores. In the normal tetrasporangium four 

 haploid tetraspore-nuclei arise from the one successful and conquering 

 nucleus. In the monospores here described the conquering nucleus is 

 itself haploid and therefore remains undivided. The views on alterna- 

 tion of generation in Florideas are therefore unaffected by the phenomenon 

 here described. The author discusses possible cytological conditions in 

 plants which bear cystocarps and tetraspores, and he finally says a few 

 words on the " paraspores " of Florideaa. 



Delesseria sanguinea.f — N. Svedelius discusses the development of 

 the cystocarp in Delesseria sanguined. He sums up his results as follows : 

 An examination of the histological development of the carpogonial 

 branch shows that its position, as also that of the trichogyne, is deter- 

 mined as soon as the first division in the carpogonial leaf takes place, 

 after the differentiation of the first pericentral cells. The carpogonial 

 branch is sometimes almost intercalary, since its second and incomparably 

 largest cell is the first formed. This cell then cuts off the first, third 

 and fourth cells fairly quickly, sometimes almost simultaneously. The 

 cell-nuclei of the carpogonial branch have generally twenty chromo- 

 somes. This can be most clearly distinguished in the second cell, which 

 possesses the largest nucleus. The carpogonium has originally one 

 nucleus. This divides then into the definite carpogonium nucleus, or 

 egg nucleus, and the trichogyne nucleus. The latter wanders out into 

 the trichogyne and dissolves. The auxiliary cell is formed from the 

 "stalk "-cell after fertilization. Before fertilization a few "sterile" 

 cells are formed from the " stalk "-cell, which immediately after fertiliza- 



* Ber. Deutsch. Bot. Gesell., xxxii. (1914) pp. 106-16 (1 pi. and 1 fig. in text). 

 + Svensk. Bot. Tidsskr., viii. No. 1 (1914) 32 pp. (2 pis. and figs, in text). 



