ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 745 



Fungi. 



Fertilisation in Plasmopara.*— 0. Rosenberg finds a great 

 similarity in the formation of the fruit between this fungus and the 

 other members of the Peronosporeas that have been examined. The 

 oogonium at an early stage is seen to be filled with protoplasm, inter- 

 spersed with many small vacuoles, and contains about 45 nuclei each 

 with a definite nucleolus and chromatin. The antheridium contains 

 about 5 nuclei and is pressed against the oogonium. A slight bulging 

 of the oogonium into the antheridium, forming a receptive papilla, takes 

 place, and later the nuclei in both organs undergo mitotic division. 

 Those of the oogonium wander towards the periphery, one only, as a rule, 

 remaining in the denser protoplasm of the centre. The coenocentrum 

 makes its appearance simultaneously with the nuclear division. The 

 central nucleus also divides, the daughter-nucleus passing outwards. 

 The nuclei all divide a second time, and the sister nucleus in the centre 

 gradually disintegrates. Owing probably to changes in turgidity the 

 receptive papilla is withdrawn and a protrusion arises from the 

 antheridium which penetrates the oosphere. One nucleus alone passes 

 into the oogonium. The writer adds details of the mitotic process. 

 The resting structure resembles the spirem stage of the higher plants. 

 Before division the nucleolus takes a lenticular shape, the Sichelstadium, 

 and the chromatin comes to lie in a ball at the side of the nucleus repre- 

 senting the synapsis stage. The nuclear spindle is formed from the 

 network of the nucleus, and the division of the chromosomes takes place 

 at the equator. The resulting nuclei are smaller and lose their nuclear 

 membrane at an early stage of their subdivision. Rosenberg thinks that 

 the Sichel and synapsis stages indicate a reduction of chromosomes, and 

 that the double division is akin to the tetrad division of the higher 

 plants. 



Action of Fermentation on the Cell.f — L. Matruchot and M. 

 Molliard conclude their study of the changes induced in the cell by the 

 fermentation process. They repeat in beetroot, and onion the observa- 

 tions already made on those of the pumpkin. They also studied the 

 changes in the cells of Mucor racemosus, a fungus which itself produces 

 fermentation. The nuclei increased to twice their original size, as in the 

 •cells of the higher plants, and decreased in number with cell-division, 

 so that each cell of the filament contained finally one or at most two 

 nuclei. Some cells were even non-nucleate. 



Spore-Formation in Mucorini.J — Deane B. Swingle gives the result 

 of his study of two members of the group Rhizopus nigricans and 

 Phycomyces nitens. He notes first the formation of denser contents, 

 cytoplasm and nuclei, towards the ^sporangium wall, followed by the 

 appearance of large vacuoles in the denser protoplasm parallel to its inner 

 surface. After the formation of the columella, furrows are formed 

 inward from the surface and outward from the columella, both systems 



* Bihang K. Vet. Akad. Handl, iii. (1903) No. 10, 20 pp. (2 pis.). 

 t Rev. Gen. Bot., xv. (1903) pp. 310-27. 



% U.S. Dept. of Agric. ; Bureau of Plant Industry ; Bull. No. 37 (1903) pp. 1-40 

 <6 pis.). See also Bot. Centralbl., xciii. (1903) p. 259. 



