JlLV 24, UWi.] 



SCIENCE. 



115 



HUURTER AiaiCLlCli. 

 CRYSTALS OF OXALATE OF LIME IN PLANTS. 



Agricultural and physiological chemists are 

 geuerally of the opinion that one of the func- 

 tions of lime in the nutrition of plants is to 

 form an insoluble compound with oxalic acid 

 and thus neutralize any toxic effect which this 

 acid might have upon the plant tissues. 

 Whether this theory is true or not it is quite 

 certain that crystals of calcium oxalate are 

 found in many plant tissues, while in some, 

 especially those developing large quantities of 

 organic acids, thej' are very abundant. A re- 

 markable occurrence of such crystals has lately 

 been disclosed by an investigation carried on 

 in this bureau by Mr. B. J. Howard, chemical 

 microscopist and histologist, on a sample of 

 Colocasia antiquorum, the well-known taro, 

 one of the principal food staples of Polynesia, 

 brought to the bureau by Mr. W. E. Safford, 

 assistant curator of the Bureau of Plant In- 

 dustrj', who is preparing a report on the eco- 

 nomic plants of Polynesia. Mr. Safford stated 

 that the intense burning and pricking sensa- 

 tion which is experienced on chewing parts of 

 certain plants, such as the Indian turnip 

 {Arismma triphyllum) and the plant above 

 mentioned, has been alleged to be due to the 

 action of the acicular crystals of calcium 

 o.xalate which are said to exist in immense 

 numbers, and which attach themselves to and 

 enter, at least superficially, the mucous and 

 other membranes with which they come in 

 contact. I requested Mr. Howard to make a 

 micro-chemical examination of this sample in 

 order to determine whether or not such crys- 

 tals were present. A simple trituration of the 

 parts of the plant, as, for instance, a leaf, in 

 water until a pulp is produced, is a sufficient 

 preparation. A small portion of the pulp is 

 placed upon a glass slide, a drop of water 

 added (or water and glycerine) covered with 

 a glass, and placed in the field of the micro- 

 scope. When thus prepared, numerous very 

 oblate spheroidal bodies were discovered with- 

 in which were enclosed fine needles in a dense 

 bundle. Some of these acicular and very long 

 delicate crystals were dissolved in hydrochloric 

 acid and were found to produce a precipitate 



of oxalate of lime when made alkaline by 

 ammonia. The crystals of oxalate of lime 

 produced in this way were not acicular as in 

 the original case, but tetrahedral. While ex- 

 amining the field of the microscope, Mr. 

 Howard observed in the case of one of the 

 oblate spheroids the projection of these crys- 

 tals into the ambient liquid with what seemed 

 to be a considerable degree of force. This 

 observation was so interesting that I requested 

 Mr. Howard to prepare another portion of the 

 material and see if the phenomenon be re- 

 peated. I first examined carefully the field 

 of the microscope as prepared, but found no 

 crystals, but a large number of spheroids 

 above mentioned in which the bundles of long 

 acicular crystals could be easily distinguished. 

 These were surrounded by a membrane of 

 quite uniform thickness, apparently of a cellu- 

 lar nature and probably consisting mostlj' of 

 a cellulose — in other words, the crystals seemed 

 to be encysted. During a period of observa- 

 tion of from five to ten minutes I did not 

 notice the recurrence of the phenomena above 

 described. Mr. Howard then observed the 

 field in the microscope, and in a few minutes 

 he said that one of the bombs had begun to 

 discharge its projectiles. I immediately took 

 Mr. Howard's place at the microscope and 

 saw, for a period of five or ten minutes, a 

 most remarkable display. Continual dis- 

 charges were made from this bomb, the ends 

 of the arrows spreading out as they emerged 

 in groups of from four to ten. As these 

 groups were finally separated from the bombs, 

 they were discharged with considerable ve- 

 locity into the ambient liquid, the bomb itself 

 suffering a corresponding recoil. I did not 

 keep an accurate account of the discharges 

 made; but I would sa3- that they would aver- 

 age not less than two per minute. Some- 

 times one or two needles only would be dis- 

 charged, projecting rapidly, and then leaving 

 the bomb finally with a sharp advance. At 

 other times, as before mentioned, groups of 

 from four to ten arrows would discharge at 

 once. The field of vision in the vicinity of 

 the bomb became partl.v covered with these 

 long crystals, but the supply within the bomb 

 did not seem to diminish materially. There 



