ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 423 



of a segment does not forthwith enable us to judge of its relative contents, 

 and difficulty occurs sometimes on this account. (2) The second funda- 

 mental principle is that which regulates the position of fluid lamellsB 

 elsewhere — the principle of least areas. The rule is that the new cell-wall 

 takes such a direction that its area is the smallest possible. There are 

 exceptions, e. g. cambium cells ; but at least one feature appears to indicate 

 a tendency to follow the principle — cell-walls never abut in the angles of 

 cells. Sachs's law of rectangular division is comprehended as a particular 

 case of Berthold's more general law : it fails where simultaneous divisions 

 result in the formation of polygonal cells — e. g. in the embryo-sac — with 

 walls inclined at angles greater than the right-angle. 



The eighth chapter deals with the sculpturing on the interior of cell- 

 walls, and allied phenomena ; while the ninth chapter is davoted to " free- 

 cell-furmation." 



Chemical reactions of Protoplasm.* — By the use of a number of chemi- 

 cal reagents, the application of which is specified — all of which dissolve 

 some of the proteinaceous constituents of the cell, leaving others undis- 

 solved — Herr F. Schwarz determines the distinctiveness of the following 

 substances, viz. — In the nucleus a ground-substance, fibrillar substance, 

 chromatin, nucleoli, and membrane. In the chlorophyll-grains a fibrillar 

 substance capable of swelling but never soluble, and an intermediate sub- 

 stance capable of both, but never a chemically differentiated membrane. 

 In the cytoplasm a fibrillar and an intermediate substance, together with 

 imbedded granules ; no chemical differentiation of the outer and inner 

 boundary of the cytoplasm could be determined. 



C2) Other Cell-contents. 



Starch, in Vessels. — In corroboration of previous observations, Herr 

 A. Fischer finds,f in fully 80 per cent, of the leaf- stalks of Plantago major, 

 starch-grains in some of the vessels and tracheids ; and the same was the case 

 also with several other species of the same genus. The starch-containing 

 tracheids are sometimes the oldest spiral vessels in the vascular bundle of 

 the leaf-stalk, sometimes the last-formed dotted vessels ; each bundle may 

 contain one or more of these tracheids ; the quantity of starch varies from 

 a few grains to a sufficient amount completely to fill up the vessel, which 

 always has a well-developed lignified wall. The starch-containing tra- 

 cheids sometimes lie in a row one behind another, but do not extend 

 through the whole of the leaf-stalk. By maceration and staining with 

 anilin-blue, the author was able to determine the invariable presence of 

 protoplasm in these tracheids, sometimes also of a nucleus. No starch- 

 producers could be detected. 



In confirmation of these observations, Herr J. Schrenk ^ states that he 

 finds abundance of starch in vessels in the haustoria of Gerardia and in 

 the rhizome of AristolocMa serpentaria. In these cases it occurs, not in 

 spiral vessels, but in vessels with bordered pits, and Herr Schrenk believes 

 that the starch was originally produced in thyllse. 



Starch and Leucites.§ — According to M. E. Belzung, grains of chloro- 

 phyll are of two different kinds, according to their origin. Chloroleucifes, 

 with an albuminoid skeleton, resulting from differentiation of the protoplasm, 



* Bf.r. Deiitsch. Bot. Gesell , iv. (1886) Gen.-Versamm]., pp. ciii.-cviii. 



t Ibid., pp. xcvii.-cii. Cf. this Journal, 1885, p. 671. 



I Bot. Ztg., xlv. (1887) pp, 152-3. 



§ Bull. Soc. But. France, viii. (1886) pp. 483-4. Cf. this Journal, 1886, p. 819. 



