244 



SCIENCE. 



[N. S. Vol. XVIII. No. 451. 



the map almost due east of Lexington, and 

 distant 51 miles. 



Two other saplings in the vicinity of where 

 No. 3 fell, distant, respectively, about 100 and 

 200 yards, in an easterly direction, have been 

 broken off by missiles striking them from the 

 west. Search for where these buried them- 

 selves in the ground was not rewarded with 

 success. 



The dent in the road made by No. 1 had 

 become obliterated, but from the accounts of 

 those who saw it soon after it was made, it 

 dipped eastward, and so is in line with the 

 evidence afforded by the other fragments. 

 Arthur M. Miller. 



State College op Kentucky. 



the protective function of raphides. 



To THE Editor of Science : In view of Dr. 

 Wiley's interesting account (printed in Sci- 

 ence of July 24) of the raphides of Golocasia 

 antiquorum, it may be worth while to quote the 

 description of these crystals and the cells 

 containing them given by Haberlandt in his 

 ' Physiologische Pflanzenanatomie,' edition 2, 

 pp. 448, 449, 1896, translating literally: 



" That in numerous cases the crystals of 

 calcium oxalate, when they occur as raphides 

 or spear-shaped crystals, are also to be re- 

 garded as functioning secondarily as a me- 

 chanical means of protection against animals 

 that would feed upon the plant, is beyond 

 doubt. Schroff has proved that the irritating 

 effect of the sap of the bulb of Scilla mariiima 

 depends upon the penetration of the skin by 

 the raphides, and that filtered sap produces 

 no irritation. Stahl * afterwards demonstrated 

 the same thing as holding true for other 

 plants, especially Arum maculatum, and 

 showed by experiment that leaves of that plant, 

 when merely treated with alcohol, were hardly 

 touched by snails, while on the other hand, 

 leaves treated with dilute hydrochloric acid, 



* The utility of raphides in protecting plants 

 from snails is quite fully discussed by Stahl in 

 his interesting paper entitled ' Pflanzen und 

 Schnecken: Eine biologische Studie iiber die 

 Schutzmittel der Pflanzen gegen Schneckenfrass,' 

 Jenaisclien Zeitschrift fur Naturw. und Med., Vol. 

 22, pp. 84-99 of the reprint. 



in which the raphides were dissolved, were 

 very quickly devoured. The ejection of the 

 numerous crystal needles from the cell con- 

 taining them is largely effected through the 

 absorption of water by the strongly swelling 

 mucilaginous substance which always encloses 

 the bundle of raphides. That the form of 

 the , containing cell, as well as the manner 

 in which its walls are thickened, is in many 

 cases an adaptation to the protective function 

 of the raphides, is indicated by the following 



"In the leaves of Pistia Stratioies [which 

 like Colocasia and Ariswma belongs to the 

 Arum family], the one-layered plates of par- 

 enchyma that make up the aerenchyma 

 (breathing tissue) contain transversely placed, 

 spindle-shaped, elongated cells [almost cigar- 

 shaped in Haberlandt's figure] containing 

 raphides. Both ends of these cells project into 

 the intercellular air spaces. The blunt ends 

 of these cells have an extremely delicate cell 

 wall, while the rest of the cell wall is rather 

 thick, although not cutinized. Upon mechani- 

 cal injury to the cell, although not, however, 

 through the simple presence of water, the 

 raphides are ejected, generally one at a time, 

 with considerable force through the swelling 

 mucilaginous envelope, whereby the thin por- 

 tion of the cell wall is pierced and soon com- 

 pletely disappears. The place of exit of the 

 raphides is in this case determined by the thin 

 part of the wall and, furthermore, the conical 

 tapering of the ends of the cells prevents the 

 whole bundle of raphides being ejected at once. 

 As the raphides are projected one after the 

 other, the attacking animal can be wounded 

 in different parts of the body." 



Thos. H. Keaeney. 



8E0RTEB ARTICLES. 

 carboniferous fossils in ' ocoEE ' slates in 



ALABAMA. 



The age of the semi-crystalline and crystal- 

 line schists which extend in continuous belt 

 from New England to Alabama, has long been 

 a subject of discussion and of wide difference 

 of opinion among geologists. On the one hand, 

 they have been considered as pre-Cambrian ; 



