Januaky 7, 1898.] 



SCIENCE. 



13 



bean seedlings being grown entirely under 

 tbe rays. Good outlines of the leaves and 

 tracings of the principal veins were ob- 

 tained, while the stems, roots and coty- 

 ledons of the pea and beans made strong 

 pictures. The contrast between the gen- 

 eral groundwork of the leaves and the 

 surrounding space is quite strong, which 

 shows that there was considerable absorp- 

 tion of the Eontgen rays even by the deli- 

 cate seedlings experimented upon, and that 

 the absence of any marked injury or other 

 influence could not be due to non- absorp- 

 tion of the rays. 



The other plant parts which were photo- 

 ^aphed by the Eontgen rays are the fol- 

 lowing : Leaves of two species of Begonia, 

 in which quite strong pictures of the leaves 

 and of the venation were obtained. The 

 venation of B, rex, with rather prominent 

 red veins coming out more strongly than 

 B, nitida-alba, both were being taken on 

 the same plate. The interior of various 

 nuts, as almond, peanut, hickorynut, makes 

 quite strong pictures. Good pictures were 

 obtained of the endosperm (prothallium), of 

 the fruit of cycas, also of the seeds of green 

 peas and beans still within the pod. Flower 

 buds of Fuschia show the pistill and sta- 

 mens in position before opening and the 

 delicate flowers of Begonia also absoi'b the 

 rays sufiBciently to be photographed, al- 

 though the picture made was weak. Fruits 

 of apricot and green fruit of the plum and 

 pea absorb the rays so strongly that it is 

 difficult to get a good contrast between the 

 flesh and stone, while the ripe fruit of a 

 black cherry (probably a variety of Prunus 

 avium) gives better contrast. The pla- 

 centa and young ovules of Podophyllum 

 peltatum show rather indistinctly through 

 the walls of the ovary. A knot in the pine 

 board makes a distinct Eontgen photo- 

 graph. The spadix and flowers of Ariscema 

 triphyllum show distinctly through the 

 spathe, and the vascular ducts of the stem 



are also photographed. In specimens of 

 Peltandra, in which the spadix was en- 

 tirely enclosed within the spathe the spadix 

 and outlines of the staminate and pistillate 

 flowers are quite distinctly shown in a 

 Eontgen photograph, while the vascular 

 ducts of the stem show quite strongly in the 

 picture (see Plate I., Frontispiece). 



It is thus seen that plant tissues absorb 

 the Eontgen rays quite freely, and it is 

 singular that there is not a more marked 

 influence on growing parts, especially that 

 there are no visible external injuries, even 

 when the parts are exposed at close range 

 a large part of the time during several 

 daj's, since the general impression is that 

 the rays, even with comparatively short ex- 

 posures, are injurious to the human tissues. 



The longer my experiments continued 

 the more mysterious the whole subject 

 seemed. On a dark night, when the elec- 

 tric-light rays were intercepted by a black 

 screen, exploring the field with a fluoro- 

 scope there was an abundance of light, 

 flashing and quivering with the variations 

 in the electric transmission through the 

 tube, penetrating, and yet capable of ab- 

 sorption to a considerable degree. That it 

 should present no easily discernible influ- 

 ence for the time during which the work 

 continued was cause for profound surprise. 



G. F. Atkinson. 

 Cornell Univbesixy. 



SOME CONSIDERATIONS UPON THE FUNC- 

 TIONS OP ST03IATA.* 



The sporophytes of many Bryophyta and 

 of all Pteridophyta and Spermatophyta have 

 their epidermis pierced with minute open- 

 ings known as stomata. These occur upon 

 particular portions of the aerial structures, 

 not being found upon roots, nor upon sub- 

 aqueous stems and leaves. They always 

 stand over masses of chlorophyll-bearing 



* Read before Section K. of the British Association 

 for the Advancement of Science, August 19, 1897. 



