ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 671 



are present, and it is only in yellow patches that recovery of the green 

 colour can occur in old age ; that where the chroinatophores do occur 

 they are smaller than u&ual. 



British Dye-plants.* — C. B. Plowright has examined and tested the 

 tinctorial properties of about 70 plants, using only the simpler mordants 

 (such as alum, ammonia, iron sulphate, &c), with a view of ascertaining 

 what shades and colours were available for former inhabitants of our 

 islands. About 150 different shades were produced, all essentially 

 sombre in hue. The author gives a list of the plants and the results 

 obtained in each case. 



Relationships of American and Old World Birches.t — M. L. 

 Fernald after a comparative study of the North American and old 

 world forms of Betula, concludes that some forms hitherto regarded as 

 endemic in the new world are identical with old world forms, thus em- 

 phasising the community between the floras of the eastern and western 

 north temperate areas. 



CRYPTOGAMS. 



Pteridophyta. 



Pollen and Male Prothallia from the Coal Measures. i— B. Renault 

 gives figures and descriptions of various preparations on which he bases 

 the following conclusions. Many pollen-grains of the coal period con- 

 tained a male prothallium perfectly well defined, the compartments in 

 which enclosed the antherozoid-mother-cells. This prothallium might 

 send out a pollen-tube as in Steplianospermum, or allow the antherozoids 

 to escape directly into the pollen-chamber as in JEtlieotesta. In cases 

 where the grain was too large to penetrate the micropylar canal to the 

 pollen-chamber, it threw off its extine, and the prothallium penetrated 

 alone ; the perforations in the cell-walls allowed the antherozoids to 

 pass into the pollen-chamber, into which the necks of the archegonia 

 opened. 



Fossil American Ferns : Fertile Fronds of Crossotheca and 

 Myriotheca.§ — E. H. Sellards describes fertile fronds of species of these 

 Carboniferous ferns from Mazon Creek, Illinois. He points out that 

 although both genera are included by Zeiller in the Marattiacese, the 

 large size of the spores and the comparatively small output to the 

 sporangium are characters not met with in the living representatives of 

 that group. The position of the sporangia is also unusual. He also 

 examined spores from a large number of fronds of two species of 

 Pecopteris from the same locality and finds no indication of heterospory, 

 and does not accept Renault's suggestion of the existence of this con- 

 dition in the genus. 



The same author, || as the result of examination of additional ma- 

 terial, concludes that Lesquereux's fern genus Icliophjllum is merely 

 a synonym of Neuropteris rarinervis BuDt. 



* Trans. Norf. and Norw. Nat. Soc, vii. (1902) pp. 383-94. 

 t Amer. Journ. Sci., xiv. (1902) pp. 167-94 (2 pis.). 

 % Comptes Kendus, cxxxv. (1902) pp. 350-3 (7 figs.). 

 § Amer. Journ. Sci., xiv. (1902) pp. 195-202 (1 pi.). 

 || Torn, cit., pp. 203-4 (2 figs.). 



