566 



SCIENCE 



[Vol. LV, No. 1430 



certain universities; and the organization of 

 adult education as an integral part of the work 

 of the universities. 



Dr. David P. Baeeows, president of the Uni- 

 versity of California, on May 16 presented his 

 resignation as president. 



Dr. George P. Cutten, president of Acadia 

 University, Nova Scotia, has heen elected presi- 

 dent of Colgate University at Hamilton, N. T. 



Dh. Alan Mara Bateman has been ap- 

 pointed associate professor of economic geology 

 at Yale University, with assignment to the 

 Sheffield Scientific School. 



DISCUSSION AND CORRESPOND- 

 ENCE 



THE CYTOLOGY OF VEGETABLE CRYSTALS 



The title of this note involves, especially to 

 those of mechanistic outlook, an apparent con- 

 tradiction in terms. It is very generally assert- 

 ed that crystals of calcium oxalate, the com- 

 monest type found in plants, are formed by the 

 ordinary processes of crystalization in the fluid 

 of the cell sap, occupying the vacuolated center 

 of the mature vegetable cell. It is the inten- 

 tion of the present preliminary statement to 

 call attention to the fact that this description 

 of the mode of formation of vegetable crystals 

 is in all respects profoundly inaccurate. The 

 commonest type of crystal of calcium oxalate 

 is the compound crystal or druse which pre- 

 vails from the Ginkgoales to the Angiospermae. 

 The most favorable object for study is Ginkgo. 

 Longitudinal and transverse sections through 

 the mature tissues as well as through the grow- 

 ing points show the presence of druses in great 

 numbers, and often of large size, particularly 

 in the pith, cortex, and phloem. In spite of 

 the presence of such crystals, sections as thin 

 as five mieromillimeters can easily be cut off 

 the tissues. When these are stained and 

 mounted the crystals stand out with particular 

 clearness as occupying practically the entire 

 lumen of the cell. 



When measures are taken to remove the 

 calcium oxalate by the use of solvents, the 

 presence of an organic matrix in the crystals 

 becomes obvious, as a residuum maintaining 



the form of the crystals after the lime com- 

 pound itself has disappeared. If sections are 

 made in proximity to the growing point, a 

 very interesting situation becomes apparent. 

 The cells in this region are densely filled with 

 protoplasm and those which are to produce 

 crystals are easily recognized from the first. 

 They contain, as do other young ceUs, a central 

 nucleus and it is obvious in demineralized sec- 

 tions that the crystals are laid down about the 

 nucleus, when the protoplasm of the element is 

 still dense and unvacuolated. From the very 

 beginning the crystals occupy practically the 

 whole lumen of the cell and more or less proto- 

 plasm surrounds the nucleus which is the 

 organic center of the druses. The crystals in 

 fact constitute an irregular spiny casing, which 

 surrounds the nucleus and protoplasm. Even 

 in very large and old crystals indications of 

 the presence of a nucleus can frequently be 

 demonstrated by appropriate methods. 



Similar observations have been made in the 

 case of crystals of oxalate of lime, so commonly 

 present as a metabolic byproduct in the 

 Dicotyledons. Particularly favorable objects 

 for such studies are the Juglandaceag, Cactacese, 

 Begoniaceee, Gerianiacese, etc. In angio- 

 spermous species the nucleus becomes obscured 

 at a very much earlier stage of development of 

 the crystal and not infrequently the latter does 

 not occupy the whole lumen of the cell as in 



Apparently the most interesting fact in the 

 present connection is that compound crystals 

 or druses are not formed in plants by the ordi- 

 nary routine of crystallization in the watery 

 fluid of the cell sap, as has been universally 

 stated and supposed; but by the action of 

 living protoplasm and under the influence of 

 the nucleus, which is central to the crystal 

 itself. Corresponding to this fact there is only 

 one druse in each cell. A further surprising 

 fact is that the cell-wall in many cases grows 

 in size to accommodate the crystal under the 

 influence of protoplasm contained within the 

 crystal itself. This condition constitutes a 

 yery serious problem for those mechanists who 

 attempt to explain all the properties of living 

 beings by the so-called artificial cell and col- 

 loidal chemistry. The crystal-containing cells 



