20 



Garden and Forest. 



[January 9, iS 



large, compressed and ovate, surmounted by a linear-lanceo- 

 late leathery leaf about a foot long. The flowers are about 

 two inches across, wavy in outline, white speckled with rose- 

 purple. This plant is found in dense forests on the central 

 Corderillas at elevations of 6,500 to 1,300 feet; consequently 

 it wild stand very cool treatment, but does best with an aver- 

 age temperature of 55°. 



Odojitoglossuin Shuttleworthce. — This is a superb species, 

 and the specimen in flower here is unique. It is presumed to 

 be a natural hybrid between O. triumphdns and O. Pescatorei. 

 The habit and intiorescence resemble the latter, but the bulbs 

 attain an immense size. The flowers are about three inches 

 across, the sepals and petals of a straw-color margined with 

 deep yellow, the sepals being spotted and blotched with cin- 

 namon red. The large pandurate lip is yellow, with a large, 

 broken blotch of reddish-brown on the crest. The plant was 

 imported among a consignment of O. Pescatorei. 



Oncidium excavatum is a very strong, fi'ee-growing kind, 

 with large, ovate bulbs, and broad, deep-green leaves about 

 twelve inches long. The strong, branching scapes are three 

 to four feet long, and bear numerous showy flowers about 

 two inches across. The sepals and petals are bright yellow 

 blotclied with brown. The lip is large, flat and of a deep 

 golden color. The crest, which is very prominent, is yellow 

 marbled with brown. This is a particularly showy species, 

 producing its flower-spikes freely, and it would also be ex- 

 tremely useful to florists for cut-flower purposes. It is a native 

 of Peru, and grows freely in a cool, damp atmosphere with the 

 Odontoglossums, but should be accorded a good rest as soon 

 as growth is finished, or new growths will appear instead of 

 flowers. 



Kenwood, N. Y. F. Goldrillg. 



Principles of Physiological Botany as applied to 

 Horticulture and Forestry. 



II. — The Contents of Vegetable Cells ; Protoplasm, or Living 

 Matter ; the Various Living Granules, or Plastids ; Rela- 

 tions OF These to Their Surroundings. 



STARTING from the point reached in the first paper of 

 this series, we recognize these facts (i), that all plants are 

 composed of minute bodies, termed cells, and of the pro- 

 ducts fonned by them ; (2), that these cells, while living, con- 

 tain active living matter, or protoplasm, in which and by 

 which all the proper work of the plant is carried on, and (3) 

 that this living matter, or protoplasm, in one cell, is practi- 

 cally continuous with that in adjoining cells, and so on 

 throughout the whole plant. 



The properties of protoplasm must now engage our atten- 

 tion, since. we cannot understand in what way all these cells 

 work harmoniously together and accomplish certain results, 

 unless we first ascertain the teachings of modern science re- 

 garding their active contents. 



It should be stated frankly at the outset, that it is a hard 

 matter for one who is not engaged directly in the study of 

 plants to get a clear notion of this part of the subject. A 

 tree appears so strong in its framework, and we have seen 

 it resist so many gales of summer and storms of winter, 

 that, as we have said before, we can hardly realize that the 

 stout framework is not alive, but is merely the mechanical 

 support of a film, or succession of films, of extremely delicate 

 cells which lie just under the protecting coats of the inner 

 bark. And it is still more difficult to realize that it is to the 

 liv-ing matter of these cells that we must look for every sound 

 explanation of the phenomena of plant life. Our present 

 course of thought must lie, therefore, for a time among the 

 things which are unseen except by aid of high powers of the 

 best microscopes. In fact, one or two of the more recent 

 acquisitions in this field have been possible only because of 

 important advances made of late years in the construction 

 of microscope lenses. 



Protoplasm, or the living matter of the cell. — This is 

 essentially the same in animals that it is in plants, and pre- 

 sents about the same phenomena. Under the microscope it 

 appears as a colorless, somewhat granular, half-liquid mass, 

 which in certain thin-walled cells, which it does not quite 

 fill, can be observed to change its shape more or less rap- 

 idly. These movements of protoplasm can be readily made 

 out in such thin-walled cells as the hairs of the Squash-vine 

 and Nettle, and in innumerable other instances may serve as 

 a good criterion of its activity. • For the examination of such 

 phenomena it is not necessai-y to use a very high power of 

 the microscope, two or three hundred diameters being suf- 

 ficient. These movements are hastened by increasing the 

 warmth of the cell up to a certain temperature, say about 



one hundred Fahrenheit ; but when we reach a temperature 

 forty or fifty degrees higher than this, all inotion stops and 

 does not begin again. If, on the other hand, we cool the 

 cell down, the motion can be retarded until, a little above the 

 freezing point of water, it is arrested, but on warming the 

 cell again, very cautiously, the movement is resumed. 



There are many ways in which the movement can' be ar- 

 rested — as, for instance, by strong electrical shock, or b)- 

 crushing, and so on ; but the only ones which need to be 

 particularly noticed now are the following: (i) by shutting 

 off all water and food from the cell, as in starvation, and (2) 

 by shutting off all Oxygen, as in preventing free access of 

 air. It is proved beyond question that when protoplasm is 

 active there is a consumption of food, Avhich, under the in- 

 fluence of the oxygen absorbed, is converted sooner or later 

 into the gas known as carbon-dioxide* and water. The latter 

 process is nothing more or less than respiration, so that we 

 liave here in the microscopic cell, two processes which are 

 essential to all activity in the animal as well as in the vegetable 

 world, namely (i), the appropriation and utilization of food, 

 and (2) respiration or breathing. No growth can take place 

 and no work can be done by the plant or by the animal if 

 either of these processes is suspended. 



But just here appears a world-wide difference between the 

 plant and the animal. The plant, by virtue of certain gran- 

 ules which its protoplasm contains, can, under certain cir- 

 cumstances to be described later, construct its own food out 

 of inorganic matters obtainable from the air and from water 

 in the soil, whereas no animal can do this. (We are leaving 

 out of account, as was explained in the introduction, some 

 interesting exceptions, which will be found explained in all 

 large works on the subject, for our purpose is inerely to 

 show what are the general cases and comprehensive rules.) 



We must now look at the granules by which plants can 

 effect this extraordinary change of inorganic into organic 

 matter. 



The cells in the green parts of plants contain, imbedded 

 in their protoplasm, minute greenish granules of various 

 shapes, generally roundish. These are known as the chlo- 

 rophyll-granules, or, what means the same thing, leaf-green 

 granules. When these are provided with a supply of car- 

 bon-dioxide in proper amount, and are exposed to sunlight, 

 they can, if all the other conditions as to warmth and so on 

 are favorable, manufacture a sort of sugar, or something 

 very much like it, giving off at the same time a certain pro- 

 portion of the oxygen which was in the carbon-dioxide. This 

 sugar, or its equivalent, is the primary food of the plant. 

 This process, which appears to be so simple, is in reality 

 very complex, and can be only partially understood even 

 after we have examined the structure of the parts where 

 most of the green granules are found in our plants, that is, 

 in the leaves. It is enough for the present to state that this 

 wonderful laboratory of a green cell constructs all the food 

 for animals, as well as for plants, since it is the excess of what 

 plants make and do not themselves consume that animals 

 employ as their food. 



One more thing should be noticed at this point, namely, 

 that part of this food made by plants is stored up in the 

 form of starch or oil for future use by them, while a large 

 part is turned to account in building up, in the form of cellu- 

 lose, or cell-wall substance, the fabric of the plant. 



We must next combine a few of the foregoing statements, 

 in order that the relations of the cells to each other may be- 

 come plain. The cells which contain the leaf-green granules 

 require for the manufacture of sugar (r) water, which comes 

 in by absorption from the immediate surroundings; (2) car- 

 bonic acid, procurable from the air; (3) light of a certain qual- 

 ity and intensity; (4) a certain temperature. Now, the green 

 cells of our trees are inainly in the leaves. The position of 

 the foliage exposes them sufficiently to light and air, while 

 communication with the soil is effected through the stem 

 and roots. In other words, millions of cells in the roots and 

 elsewhere in the plant are tributary to these green cells of 

 the transient foliage. 



Our task is now fairly before us. We are to -see in what 

 way this co-operation between the cells in the roots and 

 leaves is accomplished, and to what extent the roots, stem 

 and leaves share in all the varied work of the plant. Re- 

 serving the examination of these organs to later papers, we 

 may give a passing glance at certain curious relations which 

 have been recently discovered by Professor Schimper, be- 

 tween the leaf-green granules and other granules within the 

 cells of plants. In the cells at the growing points of plants 



* Carbon-dioxide is often termed carbonic acid, and these terms maybe used 

 interchangeably. 



