282 SUMMARY OF CURRENT RESEARCHES RELATING TO 



new and complete diagnosis of the species with synonymy, adding six 

 forms, most of which represent species hitherto known under other 

 names. 



Porphyridium cruentum.* — H. Kufferath writes a short preliminary 

 paper on Pophyridium cruentum. He finds it can only grow in light, 

 and he gives a list of the chemical substances which are favourable and 

 unfavourable to its culture. He describes the thallus with its gelatinous 

 sheath of two distinct layers, its method of multiplication, and the cell- 

 contents, nucleus, protoplasm, and granulations. He notes as a method 

 of reproduction hitherto unknown in this alga, the presence of two 

 daughter-cells in one mother-cell. Experiments were made on the 

 colouring matter. As regards the systematic position of P. cruentum, 

 it approaches Florideas in its morphological characters. In any case it 

 must not be placed in Cyanophyceae or Protococcaceas. Further study 

 of the pigment will help to elucidate the question. 



Nitophyllum punctatum. f — N. Svedelius describes the tetrad 

 division in the multinucleate tetrasporangium rudiments of Nitophyllum 

 punctatum. In a paper on Martensia in 1908, he describes a similar 

 multinucleate condition, and is able to add certain important details. 

 He finds that in the tetrasporangium-rudiments of Nitophyllum, as of 

 Martensia, the number of nuclei increases, ■ though not in so great a 

 degree. Then begins a successive degeneration, so that finally, as in 

 Martensia, only one nucleus remains, which becomes the mother-nucleus 

 of the definite tetraspore nuclei. The division of the successful nucleus 

 is a true reduction-division, as was suspected by the author in the case 

 of Martensia. The diploid chromosomes in N. punctatum (the tetra- 

 sporic plant) number 40, and the haploid chromosomes of the tetraspore 

 are 20. Another point of special interest is that each nucleus of the 

 tetrasporangium rudiments is a facultative tetraspore mother-nucleus. 

 Some of them begin to degenerate before undergoing the earliest 

 prophase of the reduction-division ; while others go through all stages 

 up to diakinesis. After that, as a rule, only one nucleus continues its 

 course, and in due time produces four tetraspore nuclei. This phenomenon 

 of the degeneration of nuclei in different stages of development is without 

 a parallel in the plant world. The author discusses the theoretic pos- 

 sibility of the perfect development of more than one of the many nuclei 

 in which case sporangia would arise containing several tetrads. In one 

 abnormal case he found a tetrad showing three tetraspores, which he 

 figures and discusses, pointing out that the power of forming tetrads is 

 not confined to one nucleus, and that the multinucleate tetrasporangium 

 rudiments in N. punctatum are entirely comparable with a multinucleate 

 archesporium of the higher plants. 



Development of the Florideae.:}: — K. Killian writes on the develop- 

 ment of the Floridere. He follows up the early stages of many species 



* Bull. Soc. Roy. Bot Belg., lii. (1913-14) pp. 2S6-90. 



t Ber. Deutsch. Bot. Gesell., xxxii. (1914) pp. 48-57 (1 pi.). 



1 Zeitschr. f. Bot., vi. (1911) pp. 209-78. 



