342 Scientific Intelligence. 



devoted to the forms, markings and distribution of the structural 

 elements. In Hofmeister's voluminous work, protoplasm and the 

 other cell-contents receive the larger share of space, and are 

 treated of as fully as the limitations of the methods then in use 

 allowed. 



By the application of improved processes of staining the con- 

 tents of cells, and especially. by the employment of the newer ob- 

 jectives, recent investigators have been encouraged to attack 

 problems which it would have been thought hopeless even to 

 approach twenty years ago. It is needless to dwell upon the 

 fact that many of these problems have not yet been satisfactorily 

 solved, and that not a few of them are still unanswered. 



The present sketch will allude to a few of the contributions 

 published during the last year or two, and an attempt will be 

 made to indicate some of the relations to what has been previ- 

 ously known. 



In extended studies by Reinke and Rodewald (1881) on the 

 chemical character of protoplasm, it was stated that the reaction 

 is alkaline. By careful microchemical studies of cell-contents, 

 Schwarz (1887) has ascertained by the use of an infusion of red- 

 cabbage that the reaction of cell-sap is sometimes acid and some- 

 times alkaline, but that of the protoplasmic mass is always alka- 

 line. This alkalinity he ascribes to the presence of potassium 

 compounds, presumably proteid combinations. The acid reaction 

 detected in the case of old cells when all the contents are placed 

 in contact with test paper is due to the considerable excess of 

 acid cell-sap. 



Schwarz has extended his studies to certain points regarding 

 the structure and chemical constitution of protoplasmic contents 

 of the cell. Recent writers have distinguished more or less com- 

 pletely and with considerable diversity of nomenclature, between 

 the general protoplasmic mass of the vegetable cell and its differ- 

 entiated protoplasmic contents. The latter, which are always 

 imbedded in the former, are known as the nucleus and the chro- 

 matophores : the mass in which they are held is termed the cyto- 

 plasm. The chromatophores are three, namely, starch-accumu- 

 lators, color-granules, and chlorophyll-granules. It is with the 

 characters of the cytoplasm, nucleus and chlorophyll-granules 

 that Schwarz has been specially engaged.. Concerning the for- 

 mer, he says that in Cytoplasm there exists no normal network, 

 but that a part of the mass can under certain circumstances be- 

 come transformed into threads and constitute the well-known fi- 

 brillse. Cytoplasm is to be regai-ded as a mixture in which under 

 certain conditions there can be a separation of its solid, viscid 

 and fluid substances. The microsomata (the very minute gran- 

 ules which occur in the cytoplasm) are sometimes of the nature 

 of precipitates. 



In the nucleus, Schwarz discriminates between (l) a fibrillar 

 framework, (2) a basic substance, (3) nucleoli, and (4) an envelop- 

 ing membrane. The chemical constituent of the framework is 



