ZOOLOGY AND BOTANY, MICROSCOPY, ET< . 315 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 including: Cell-Contents. 



Bivalence of the Chromosomes.* — J. P. Lotsy discusses, with the 

 aid of diagrams, the question of the behaviour of the chromosomes in 

 the reducing divisions of animals and plants. He concludes that there 

 is a true qualitative reducing division, since while the somatic cells have 

 bivalent, the sexual cells have only univalent chromosomes. 



Amitosis in Plants. — W. v. Wasielewskif and B. Nemec| have 

 investigated the effects of chloral hydrate in dilute solution upon the 

 division of the nucleus, especially in the roots of seedlings. Both find 

 that treatment with this reagent causes very abnormal nuclear divisions 

 and even multinucleate cells, but that if the treatment is not prolonged, 

 the nuclei and cells return later to their normal state and divide in a 

 typical way. Wasielewski believes, however, that the abnormal divisions 

 are real direct divisions (amitoses), while Nemec is of the opinion that 

 they are merely abnormal mitoses in which, however, the processes of 

 chromosome formation and splitting still occur. Nemec found that by 

 fusion of the abnormally produced nuclei, there were produced nuclei 

 with a double number of chromosomes ; presumably a reduction-process 

 occurs later, for such double numbers soon ceased to be seen. 



Reduction Division in Ferns.§ — R. P. Gregory has examined the 

 early stages in spore-formation in various members of the Polypodiaceaj, 

 and finds that the essential features of the reduction-phenomena recently 

 described by Farmer and Moore are present in ferns. The author de- 

 scribes the details of the reduction division in the spore-mother-cells. 

 The result is a transverse true reduction division of the bivalent chromo- 

 somes which characterise the heterotype division. He then proceeds to 

 a discussion of the significance of the reduction division in connection 

 with Mendelian segregation. Viewed from this standpoint the occur- 

 rence of a qualitative reduction in plants, as well as in animals, is 

 extremely important as affording a possible provision for that purity of 

 the gametes, in respect of allelomorphic characters, which is demanded 

 by Mendel's hypothesis. 



Formation of Anthocyan.|j — T. Ichimura has studied the formation 

 of this pigment to which are due the different shades of red and blue 

 found in plant organs, for instance, in the skin of many ripe fruits, in 

 some young shoots, and in various flowers. The object studied was the 



* Flora, xciii. (1904) pp. 65-86 (19 figs.). 



t Jahrb. wiss. Bot., xxxix. (1904) pp. 581-606 (figs, in text). 



j Tom. nit., pp. 645-730 (figs, in text). 



§ Proc. Roy. Soc, lxxiii. (1904) pp. 86-92. 



|| Journ. Coll. Sci. Imp. Univ. Tokyo, xviii. (1903) art. 3, pp. 1-18 I pi.). 



