Botany and -Zoology. 419 



Specific gravity 2-941 at 24°. The air dried material loses 6 -02 per 

 cent of water at 100°. The following analysis is on material 

 dried at 100°. 



Si0 2 Ti0 2 A1 2 3 Fe 2 3 CaO MgO P 2 5 H 2 

 1-76 61-54 17-59 4-46 0-90 tr. 4-17 9-92=100-34 

 Laboratory, U. S. Geol. Survey,. Washington, D. C. 



III. Botany and Zoology. 



1. Recent contributions to our knowledge of the vegetable cell. 

 (Second paper, continued from page 344.) — Loew and Bokoekt 

 distinguish between active and passive albumin in vegetable cells. 

 The former is characterized by its great chemical instability, and 

 especially by its property of reducing silver solutions even when 

 they are very dilute : the latter, on the other hand, is relatively 

 stable and is not readily changed or oxidized. These distinctions 

 have been pointed out by the authors in various communications, 

 more recently in a treatise on certain relations of protoplasm. 

 According to them, active albumin, in combination with water, 

 forms all living protoplasts, and, at the death of the cell, passes 

 over into " common " or passive albumin. The authors (Bot. Zeit., 

 Dec. 30, 1887) announce that they have detected active albumin 

 also in cell-sap in many species of Spirogyra. From its solution 

 in cell-sap it is precipitated whenever a dilute solution of amnio- 

 nic carbonate is allowed to act on the cells. A granular precipi- 

 tate appears not only in the plasma-membrane where the granules 

 are confined within or are attached to the membrane, but in the 

 cell-sap as well, the latter granules settling, after a time, to the 

 lower part of the cell. These granules do not occur in either the 

 membrane or the cell-sap if the cell has been previously hilled by 

 pressure, cutting, or by chemical means. 



It is interesting to compare these statements with those made 

 by Charles Darwin and others. The views of Mr. Darwin are 

 well known by readers of his Insectivorous Plants (see page 39), 

 and need not be further alluded to here. Pfeffer explains the 

 appearance of aggregation in a different way: he regards the pre- 

 cipitate as consisting of tannate of albumin, which forms on 

 account of the neutralization of the cell-sap by means of the am- 

 nionic carbonate. Pfeffer calls attention to the fact that the pre- 

 cipitate re-dissolves when an organic acid, for instance, citric, is 

 added, and falls again when the sap becomes again alkaline. He 

 has shown that the precipitation is effected by the addition of a 

 tenth per cent solution of ammonic carbonate, and that re-solution 

 occurs when a two-hundredth of one per cent solution of citric 

 acid is employed. Loew and Bokorky state, however, that the 

 cell-sap of Spirogyra is not acid in reaction, and that it contains 

 no free acid. Therefore, according to them, Pfeffer's explanation 

 of the phenomena is not satisfactory. The so-called " aggrega- 

 tion " is, as Francis Darwin and others have pointed out, a com- 

 mon occurrence in many cells. It appears to demand further 

 investigation. 



