170 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



GENERAL, 



Including* the Anatomy and Physiology of Seed Plants. 



Cytology, 

 Including- Cell-Contents. 



Nucleolus of Spirogyra and Chromosomes of Higher Plants.* 

 A. Trondle has studied the nucleolus of different species of Spirogyra 

 and compared it with the chromosomes of higher plants. The results 

 of the investigation show a surprising agreement in structure and 

 character, while the nucleolus of higher plants is quite different from 

 that of Spirogyra. Both the chromosomes of higher plants and the 

 nucleolus of Spirogyra behave similarly towards weak and strong acids 

 and weak alkahs, and both can be stained with acid aniline dyes ; this 

 makes it probable that they both belong to the nucleoproteids. The 

 slight difference noticed in the action of hot water, may be regarded as 

 the result of a slight difference in the amount of free nuclear acid 

 present. While the behaviour of the nucleolus of Spirogyra towards 

 chemical reagents does not exclude the possibility of the presence of a 

 glycoproteid, other considerations make this improbable. 



The author agrees with Meunier, Carnoy, and also with those modern 

 cytologists, who maintain that the nucleolus of Spirogyra is equivalent 

 to the chromatin of higher plants, and that in Spirogyra the chromo- 

 somes arise from the nucleolus. 



Reduction-division in Fuchsia. f — B. McAvoy has investigated the 

 nuclear division in Fuchsia speciosa, and finds that in the reduction 

 stage, there is an end-to-end fusion of the univalent chromosomes, 

 followed by the formation of a spireme and a definite number of loops, 

 representing incipient bivalent chromosomes. Prior to the synaptic 

 conjugation, masses of chromatin form a definite mosaic in the nucleus ; 

 these masses gradually form themselves into granules connected by a 

 delicate thread. Subsequently the nucleus swells and the chromatin 

 masses collapse in a mass, either at the side or around the nucleolus, 

 although the latter may also be quite independent. The loops which 

 appear after the spireme stage are fourteen in number, and they thicken 

 and tighten into various sizes and shapes ; the fully formed chromo- 

 somes are connected by delicate threads. 



The formation of the microspores is irregular, frequently as many 

 as eight being formed in one sporocyte. 



Evolution of the Chalazogams.:|: — S. Nawaschin and W. Finn dis- 

 cuss the significance of chalazogamy arising from a study of Juglans 



* Zeitschr. Bot., iv. (1912) pp. 721-47 (1 pi.) 



t Ohio Nat., xiii. (1912) pp. 1-18 (2 pis.). 



X Mem. Soc. Nat. Kieff, xxii. (1912) pp. 1-85 (4 pis.). 



