654 



SCIENCE. 



[N. S. Vol. VIII. No. 202. 



The leaves to be studied are placed in 50 

 per cent, alcohol to remove the chlorophyll, 

 and are then passed into a weak solution 

 of iodine. In a few hours, if the leaf is 

 thin, the starch responds to the iodine test 

 and is located by the blue color it assumes. 

 Tested in this way the parts of plants 

 which are attacked by fungi, e.g., leaf spots 

 due to Peronospora, Cystopus, Synchytrium 

 and Puccinia, and galls due to Cystopus, 

 Gymnosporangium, Plasmodiophora and 

 Ehizobium show a marked accumulation of 

 starch. The starch is either in the dis- 

 colored spot or immediately around it. 

 This distribution is very striking in the 

 leaves of Podophyllum attacked by Puccinia 

 podophylli, starch being abundant in the 

 well-defined areas, while none was met 

 with beyond the small veins that served as 

 boundaries to the infested portions. The 

 galls of peach roots, the cause of which is 

 still unknown, are gorged with starch. 

 Turnips affected by club root carry a large 

 amount of starch, while the healthy tissue 

 is comparatively free from it. In like man- 

 ner, the root tubercles of the Leguminosse 

 contain much starch, while the roots which 

 bear them are comparatively free from it. 



The Effect of an Atmosphere of Ether upon 

 Seeds and Spores. Dr. C. O. Townsend. 

 In order to determine the effect of ether 

 upon the germination of seeds and spores 

 a series of air-tight damp-chambers hold- 

 ing one litre were prepared. After soaking 

 the seeds for twenty-four hours in pure 

 water they were transferred to the damp- 

 chambers which contained respectively 

 1, 2 J, 5 and 10 cc. of ether dissolved 

 in 100 cc. of water. One chamber was left 

 free from ether for comparison. It was 

 found that 1 cc. of ether hastened the pro- 

 cess of germination slightly, but the subse- 

 quent growth of the seedlings was some- 

 what retarded by the action of the ether. 

 In the chambers containing 2J and 5 cc. of 



ether the process of germination was re- 

 tarded. The amount of retardation varied 

 from a few hours to several days, depending 

 upon the strength of the ether atmosphere 

 and upon the kind of seed used. An at- 

 mosphere containing 10 cc. of ether pre- 

 vented the seeds from germinating. If the 

 seeds were removed from this strong atmos- 

 phere of ether at the end of from seven to 

 ten days, and placed under favorable condi- 

 tions, they germinated as readily as if they 

 had not been placed in the ether atmos- 

 phere. On the other hand, if the seeds re- 

 mained in the strong atmosphere of ether 

 two weeks they seemed to lose their vi- 

 tality. 



The influence of an ether atmosphere 

 upon spores was investigated by placing 

 the spores upon plates of gelatine contain- 

 ing 10 cc. of sugar. These plates were then 

 placed in damp-chambers containing jL, 2i, 

 5 and 10 cc. of ether, one chamber remain- 

 ing free from ether for control, the spores 

 in the atmosphere containing ^V cc. of ether 

 germinated a little earlier than did those in 

 the ether-free atmosphere, while those in 

 the stronger atmospheres of ether were re- 

 tarded in germinating. Not only did the 

 spores continue to live in the atmosphere 

 containing 10 cc. of ether, but they were 

 able to germinate in about ten days with- 

 out removing from the ether atmosphere. 

 The amount of retardation was found to 

 depend upon the strength of the ether at- 

 mosphere and upon the kind of spores. 



The Toxic Action of a certain Group of Sub- 

 stances. Dr. Eodney H. True. 

 Zoologists and botanists have long re- 

 garded certain salts, of which sodium chlo- 

 ride and potassium nitrate are commonly- 

 used representatives, as being essentially 

 lacking in toxic action and operative only 

 through their osmotic activity. In this 

 study cane sugar was assumed to be a 

 purely osmotic agent, and the concentration 



