250 



THE POPULAR SCIENCE MONTHLY. 



linger adds, and his warning will carry great 

 weight, " is an important matter, and, al- 

 though likely to be in practice neglected at 

 first by the public, may probably impress 

 itself upon them in an unwelcome manner '''' 

 — that is, by a serious outbreak of trichino- 

 sis, or some other form of parasitic disease. 



CnltiTating Disease. — The virulence of 

 the yellow fever in Memphis is easy to ac- 

 count for when the sanitary conditions of 

 that city are understood. Two or three years 

 ago we published some mortality statistics 

 concerning this place, which appeared to 

 show that it is exceptionally unhealthy. It 

 would indeed be nothing short of a miracle 

 if Memphis were a healthy city with its 

 highly insanitary surroundings. The situa- 

 tion is thus described in the Lancet mid 

 Clinic, by Dr. S. H. Collins, a Cincinnati phy- 

 sician, who rendered efficient service in Mem- 

 phis as a volunteer during the prevalence 

 of the epidemic : " Memphis is situated 

 upon the east bank of the Mississippi, upon 

 a bluff varying from fifteen to fifty feet in 

 height. Upon the crest of this blulf runs 

 Front Street; from this street the ground 

 slopes eastwardly away from the river, so 

 that all rain, surface-gutter washings, slop, 

 and whatever of floatable filth there may 

 be, is drained into the bayou, which winds 

 about through the heart of the city. Across 

 the river the Arkansas shore stretches low 

 and flat, a vast marsh, notorious for its ma- 

 laria ; north and east of Memphis upon the 

 Tennessee side, the land is low and swampy ; 

 the soil in and about the city, of clay. The 

 bayou runs through the most thickly-popu- 

 lated parts of Memphis; into this elongated 

 cesspool is collected all the floating filth of 

 a city of 55,000 inhabitants ; garbage, the 

 drainings from privy - vaults, gutter and 

 street washings, dead animal matter, all and 

 everything is poured or thrown into this 

 receptacle, there to decay and fester under 

 the broiling sun of that southern climate. 

 Consider it, if possible — ten miles of reek- 

 ing rottenness ! Not a yard of it covered 

 except where crossed by the bridges of the 

 various streets. During a rise of the Missis- 

 sippi the back-water fills this bayou bank- 

 full, its accumulated filth then soaking into 

 the clay of its banks. When the river falls, 

 the current of the bavou is not of sufficient 



strength to empty its contents into the 

 river. The streets of the city of Memphis 

 are beyond description filthy, and completely 

 out of repair ; the wooden pavement is the 

 one in use, or rather was the pavement 

 originally put down. The streets and yards 

 are heavily shaded — the magnolia being the 

 tree mostly used." 



The Movements of Plants.— After much 

 patient study of the phenomena kno^^'n as 

 heliotropism and the sleeping and awaking 

 of plants, M. Paul Bert, in a memoir ad- 

 dressed to the Paris Academy of Sciences, 

 an abstract of which is published in the 

 Revue Scientijique, offers an ingenious theo- 

 ry to account for them. The swelling of 

 the flower or leaf stem just below these 

 organs has long been recognized as the seat 

 of the movements in question, and hence 

 it has been called the " motor-swelling " 

 {reuflcmcnt moteur). The movements are 

 directly produced by changes in the energy 

 with which the renjlement moteur sup- 

 ports the flower or leaf, and this energy 

 is greatest at night. For a long time the 

 author was baffled in his investigation of 

 the matter constituting the "motor-swell- 

 ing." Nevertheless, after a protracted se- 

 ries of minute observations, he recognized 

 in the glucose the fundamental cause of 

 the periodic movements. It is known that 

 this substance is formed under the action 

 of solar light, that it is decomposed in 

 darkness, or that it migrates and some- 

 times accumulates at different points of 

 the plant organism. Now, one of these 

 points is the renjlement moteur, and it is 

 very plain that its quantity there varies at 

 the different stages of the diurnal life of the 

 plant. Thus the greater part of the phe- 

 nomenon is due to the storing up and then 

 to the destruction of the glucose, the hydra- 

 tion of which produces the energy of the 

 motor-spring. The same explanation serves 

 to account for heliotropism, another phe- 

 nomenon due to the action of the highly- 

 refracting rays of the spectrum on glucose 

 or on its hydration. Inasmuch as the ac- 

 tion of these rays lessens the tension on 

 that side of the " motor-swelling " on which 

 they fiill, the opposite side gains a relative 

 increase of energy, and hence results a cer- 

 tain motion ; and, as the sun moves on 



