ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1033 



moisture, are best explained by the assumption of unequal contrac- 

 tions of the unequally thickened parts of the cell-walls ; a thin semi- 

 cylindrical cell-wall contracting more strongly than the thickened 

 inner wall of the same cells. The thickened radial walls act as arms 

 of a lever. 



The bursting of anthers was investigated chiefly in Berberideae 

 (Mahonia intermedia and Epimedium alpinum), Laurineas (Laurus 

 canariensis), Hamamelide^ (Trichocladus crinitus), and Eanunculacese 

 (Adonis autumnalis). No contraction was shown in any direction by 

 the epidermis. The cause of the unrolling of the wall of the anther 

 must be sought in tensions of the inner fibrous layer of cells, of such 

 a nature that the wall of the loculi, which is nearly uniform in thick- 

 ness, exhibits considei'ably less power of contraction than the radial 

 walls, the contraction of which causes the rupture of the anther, the 

 thickenings contained in them acting as arms of a lever. 



Root-organs of Nepkrolepis.* — In pursuing his examination of 

 the underground stems and roots of ferns,! M. P. Lachmann has 

 paid special attention to organs j^yroduced from the stem of Neplirolepis, 

 below the base of the leaves, which have been regarded by some 

 authors as cauline, by others as radicular. He finds that when the 

 main stem has produced a dense rosette of leaves, it puts out from 

 beneath each leaf a stolon, which sometimes developes into an aerial 

 flagelliforra organ, which branches only slightly or not at all, and some- 

 times buries itself in the soil, and branches like a root. Sometimes 

 both these organs are found beneath a leaf, and each has then its 

 characteristic fibro-vascular structure. The diameter of the stolons is 

 usually about 2 mm., while that of the roots rarely exceeds "5 mm. 



Apex of the Root in Osmunda and Todea.J — Prof. F. 0. Bower 

 regards the leaf of Osmundaceje as exhibiting an intermediate condi- 

 tion between that of the leptosporaugiate ferns and the Marattiaceae ; 

 the structure of the meristem of the root showing also a similar 

 transition ; this is best shown in transverse sections. In this way 

 three distinct types may be determined, viz. (1) a single three-sided 

 apical cell ; in the Equisetacese and Polypodiaceae ; (2) a single four- 

 sided apical cell ; (;->j a group of three equivalent initial cells. In- 

 termediate Conditions are found; but not the group of four initial 

 cells, which Strasburger describes in the Marattiaceae. The three- 

 sided apical cell is always pyramidal, and the group of three have also 

 always a truncate-pyramidal form. There does not appear to bo the 

 same regularity in the succession and position of the dividing-walls 

 as in the Equisetaceae and in many ferns. A similar variety is 

 apparent in the development of the lateral roots. 



In Todea harhara the author observed as a rule a group of four 

 initial cells, v hich arc eitlier pyramidal or truncate-pyramidal ; but 

 with irregularities both in the origin of the lateral roots and in the 



• 0)rnptf;H Rf;ndu8, <i. (188.')) pp. 003-5. 

 t Se«; UiiH Joiirria), iv. (1884) p. 5fJ2; ante, p. 830. 



t Quart. Joiirn. Micr. Sci., xxv. (1885) pp. 75-103 (2 pis.). See tliiu Journal, 

 iv. (1884; J). 'J23. 



