34 



Garden and Forest. 



[Number 256. 



Orchis spectabilis, so common in some of our New England 

 woods, is somewhat difficult to establish, but is well worth 

 extra trouble. Leaf-mold and sand is the best soil for it, and a 

 mulch of old leaves, broken up tine, should be placed over it. 

 It may be transplanted when in full bloom, or if strong plants 

 are set out in autumn they will usually tlower the next season. 

 It needs shade, moist, but well-drained, soil, and a light cover- 

 ing in wintering. 



Of the Rein Orchis (Habenaria), the two purple-fringed 

 species of New England, H. fimbriata, which liowers in June, 

 and H. psycodes, which comes in July and August, are some- 

 what alike in their general appearance. They grow in similar 

 locations and the same treatment will answer for both. They 

 like shade and a dark peaty soil, with plenty of moisture. It 

 is necessary to give them a good mulch as well as a well- 

 prepared soil if they are planted in ordinary garden ground. 

 They grow in wet places, but will not bear any stagnant 

 moisture. 



The Yellow-fringed Orchis, H. ciliaris, with its orange-yellow 

 flowers, likes a sandy soil best. It also needs plenty of mois- 

 ture. It should be protected from sudden changes by a light 

 mulch. It is perhaps the best Habenaria we have for cultiva- 

 tion. 



The white-flowered H. dilatata of our cold northern bogs 

 will thrive in peat or sand. Its pearly white flowers are quite 

 fragrant and beautiful. A cool spot, shade and moisture are 

 necessary for it in cultivation. 



Adam and Eve, or Putty Root (Aplectrum hiemale), is one 

 of the species of Orchids which sends up its dark green leaf 

 late in autumn. These last until the flowering season of the 

 next year, when they die down. The flowers are not very 

 showy, but the large single green leaf in autumn and early 

 spring is interesting, and it grows easily in ordinary gardens. 

 It is a deceptive plant in cultivation, since its leaf disappears 

 at the time other plants are in full growth, coming up again 

 just before winter. 



The Rattle-snake Plaintain (Goodyera pubescens) is valued 

 more for its strongly white reticulated leaves than for its short 

 spike of pretty white flowers. The leaves endure through the 

 winter, and in spring are quite conspicuous when the snow 

 first disappears. This species must have perfect drainage and 

 a rich dark soil. 



Only the strongest-flowering plants should be grown, and 

 with tliese one or two flowering seasons are pretty sure to fol- 

 low if anything like fairly good treatment is given, and they 

 will repay the trouble and expense ; weak plants may never 

 bloom, and the results at best are not satisfactory. Most of 

 these species may be transplanted either in spring or in 

 autumn with fairly good results, or even at their flowering 

 season. But spring is probably the best season when this is 

 possible, when the plants can be set before they begin to 

 grow. 



Charlotte, vt. F. H. Horsford. 



The Forest. 



Hygienic Significance of Forest Air and Forest Soil. 



MUCH has been written and said about the influence of 

 forests upon the health of mankind, and many differ- 

 ences of opinion as well as ignorant conjectures have com- 

 bined t© increase the confusion surrounding the subject. In 

 our time, when so much attention is given to physical well- 

 being, it seems the duty of science to make clear a more exact 

 knowledge of the matter based upon accurate observations. 

 Every one agrees that a residence in the country among the 

 mountains, by the sea or near great forests is more conducive 

 to health than a continual breathing of the impure, smoky air 

 of the great cities, impregnated with dust and rich in bacteria. 

 Health resorts have been preferably established in forest 

 regions, and various explanations of the healthfulness of forest 

 life have been given. The protection alforded by the trees 

 against the sun, the high percentage of oxygen and ozone in 

 the forest air due to the assimilation of carbonic acid by the 

 foliage, and, finally, the influence which the trees in the pro- 

 cess of transpiration exert upon the moisture of the atmos- 

 phere and the amount of water remaining upon the ground — 

 all these single or combined conditions have been cited as the 

 effective salubrious principle. Yet the exact scientific basis 

 for all these theoretical explanations has been scanty, and it 

 seems that, according to more careful investigation, some of 

 them will have to be relegated to the realm of pleasing fancy. 

 One of the first tofall is the oxygen theory. Although, no doubt, 

 the respiratory action of all green plants, and forest trees in 

 particular, changes a part of the carbonic acid of the air into 



oxygen, the carbon being consumed by the trees in making 

 the wood, yet the amount of oxygen exhaled by a forest when 

 assimilating carbonic acid is, according to the calculations of 

 Dr. E. Ebermayer, a most excellent authority, proportionately 

 to the needs of animal respiration, so insignificant as to make 

 the special sanitary significance of small woods or street or 

 park trees in large cities irrelevant from this point of view. 

 The daily consumption of one person in respiration is 475 

 quarts of oxygen, equivalent to the oxygen exhalation of two 

 square rods of forest area, but when we add the consumption 

 of oxygen in burning fuel every two persons would require 

 one and a quarter acres of forest to supply all the oxygen 

 needed. Take, in addition, the consumption of animals — a 

 herd of forty sheep consumes more oxygen and exhales more 

 carbonic acid than one acre of forest exhales and consumes — 

 and the irrelevancy of this supply of oxygen will be evident. 

 This does not, however, entirely exclude the limited useful- 

 ness of forest growth in that direction. It is a fact that in and 

 near forests greater amounts of ozone are found in general ; 

 but although this " condensed oxygen " has been often claimed 

 as a special health-restorer, its significance as a hygienic factor 

 is still doubtful. 



Dr. Puchner, in his very extensive measurements of car- 

 bonic acid contents in the atmosphere under different con- 

 ditions, found great irregularities in time as well as in local " 

 distribution. In a total of 162 cases, the amount of carbonic 

 acid in the forest air exceeded that in the open in 108 cases, 

 only forty-one cases showed less than the open, and in 

 thirteen the proportions were equal. This surprisingly greater 

 proportion of carbonic acid in forest air than in the open is 

 easily explained by the decomposition of the forest litter which 

 gives rise to this gas. It also varies according to seasons. In 

 winter-time the difference is inconsiderable, while in summer 

 it becomes proportionately greater. According to Dr. Eber- 

 mayer, the air in the forest soil contains less carbonic acid 

 than that of the field, varying from three to four times less in 

 winter to five to six times less in summer, the reason being 

 that the vegetable matter in fields decomposes much faster 

 than under forest cover. 



While the chemical purity of forest soil and air, with refer- 

 ence to oxygen and carbonic acid distribution, remains doubt- 

 ful, we nevertheless know that, like sea and mountain air, 

 forest air is freer from injurious gases and dust particles ; 

 furthermore, the shade and the process of assimilation and 

 transpiration have a cooling effect in the day, especially in 

 summer-time, and a warming effect at night in winter, so 

 reducing the extremes of temperature. The forest protec- 

 tion against winds is also undoubtedly of great value for pro- 

 modng health conditions. Finally, the psychic influence is 

 not to be forgotten, and we may consider tfie sanitary im- 

 portance of the forest from these considerations alone as 

 scientifically established. The main agency of the healthful- 

 ness of forest air is, however, the comparative absence of 

 bacteria, and this is mainly due to the conditions of forest 

 soil. 



Since cholera, typhus, yellow fever and malaria are soil 

 diseases of miasmatic origin, according to Dr. Pettenkofer, 

 the forest soil becomes important in its relation to this phase 

 of the subject. There are two classes of bacteria. Saprophy- 

 tic bacteria are those which thrive upon decomposing animal 

 or vegetable matter. Pathogenic bacteria, or disease germs, 

 on the contrary, demand for their full cycle of development 

 living organisms, although existing also outside of them. 

 The vegetable matter in the forest soil is deficient in albumi- 

 noids, potash, phosphates and nitrates, and is therefore less 

 nutritive for bacteria than field, garden or city soil. Tempera- 

 ture and moisture conditions in the forest soil are also differ- 

 ent and less favorable to microbe life, which thrives best with 

 certain temperatures and an alternation of dry and wet as is 

 found in unshaded fields. 



While, therefore, forest soil encourages saprophytic de- 

 velopment, no pathogenic bacteria have as yet been found in 

 it, proving it pure soil hygienically. Since bacteria get into 

 the air only wheij the upper-soil strata dry out and the wind 

 raises the dust with its bacterial germs, it is natural that with 

 less liability to dryness in the upper soil and soil cover and 

 absence of winds, the air in the forest must be freer from 

 such germs. It would probably be entirely free, or nearly so, 

 of pathogenic germs if they were not carried in from the 

 outside. But in this respect, too, a filtering process takes 

 place, at least, whether due to the reduction of velocity of the 

 wind, or to the obstacles to movement in the trunks of trees, 

 either of which would make the germ fall to the ground, and 

 the forest air contains fewer microbes. This has been 

 actually ascertained by two Italians, Serafini and Avati'a, who 



