APRIL 



The Weekly Florists* Review* 



543 



Chrysanthemums in April. 



ria, and carry on the work until the 

 food substances are enabled to start 

 again in the food cycle. There are 

 several kinds of nitrifying bacteria 

 each of which performs a certain part 

 of the work of producing the nitrates. 

 It seems that pure ammonia is affected 

 by one kind of nitrifying organism, 

 while the nitrite.s are built into ni- 

 trates by another kind. We do not 

 know definitely just how many kinds 

 of nitrifying bacteria there are, but 

 several have been identified. 



We are in no danger of attaching 

 too great importance to the work of 

 these bacteria which bring about de- 

 cay. The bodies of plants and animals 

 at the time death occurs are entirely 

 too complex to be used again by plants 

 as foods. We could not nourish our 

 plants directly by giving them the 

 flesh or bones of an animal. For a 

 long time we have known that such 

 things are entirely too complex and 

 must be reduced to far simpler forms 

 before plants can again use them. We 

 have not known very long the signifi- 

 cance of this reduction of complex 

 substances to simple ones. We do not 

 yet thoroughly understand the pro- 

 cess. 



It has been definitely determined 

 that in the absence of bacteria and 

 whatever there may be of animal or- 

 ganisms which have to do with decay, 

 no decomposition can take place. Many 

 experiments have been made which 

 show conclusively that should a piece 

 of flesh be kept free from these scav- 

 engers it would maintain its structure 

 for an indefinite period. Such men as 

 Tyndall and Huxley gave much of 

 their time in showing this to be true. 

 If bacteria were not present in nature 

 we should have all dead bodies of 



plants and animals remaining on the 

 surface of the earth, undeconiposed 

 except as affected by action of wind, 

 water and change of temperature; and 

 the time would be surprisingly short 

 until we should find our usual walks 

 obstructed by the accunnilation of 

 lifeless forms. And the inconvenience 

 this developed would be slight indeed 

 in importance as compared with an- 

 other phase of the question. We have 

 seen how the green plants under the 

 influence of the sun take water and 

 carbon dioxide and carry them 

 through various changes until we 

 reach the substances we know as 

 starches and sugars. We know 

 that before these starches and 

 sugars can be made into plant 

 and animal tissue they must be 

 worked over into new compounds to- 

 gether with certain salts of nitrogen, 

 sulphur, iron, etc., which are obtained 

 from the soil. Now should these ni- 

 trogen salts be taken constantly fi'om 

 the soil, and its supply never replen- 

 ished from the usual sources by de- 

 composition of organic bodies, it is 

 evident that the supply would soon be 

 exhausted and all plant life must end 

 since the means of supporting it are 

 no longer present. And if plant life 

 ends animal life must surely end 

 since the latter is directly dependent 

 upon the former. 



In actual practice any natural defi- 

 ciency is frequently met by the intro- 

 duction of fertilizers. These may be 

 classed under two general heads. 

 Those which are the direct organic 

 products of animals or plants — usually 

 of animals — and those which are man- 

 ufactured from such products and also 

 from certain chemicals which supply 

 the soil with some of the needed salts. 



Almost all of these, however, must be 

 worked over by the bacteria before 

 Uicy are suitable food substance for 

 growing plants. The economic signifi- 

 cance of the addition to the soil of 

 most fertilizers is not that substances 

 are introduced which may be trans- 

 formed directly into plant tissue, but 

 rather that these fertilizers form suit- 

 able food for the bacteria of decompo- 

 sition and that as these bacteria use 

 up the part of the organic matter 

 which is desirable from their point of 

 view, they form other substances 

 which can then be utilized by higher 

 plants. Doubtless some fertilizers have 

 been acted upon by the bacteria of 

 decomposition before being put upon 

 the market, in which case they re- 

 (luire less time before being actually 

 utilizable; but this saving of time does 

 not compensate for the loss by such 

 a method of things which would en- 

 rich the soil and which would not be 

 lost should the decomposition have 

 taken place in connection with the 

 soil. As a consequence that soil is al- 

 ways better which has bet-n enriched 

 by the slow decomposition of a cer- 

 tain amount of organic products, rath- 

 er than by the addition of the same 

 amount of partially decomposed or- 

 ganic products. It is true, however, 

 that such advantage could easily be 

 offset by the addition of larger 

 amounts of partially decomposed sub- 

 stances. 



But whether all of this decomposi- 

 tion which is to enrich the soil takes 

 place in the presence of the soil or 

 elsewhere, the action of the bacteria 

 bringing about the decomposition is 

 none the less significant. We find the 

 organized bodies of animals and plants 

 which contain large amounts of highly 

 organized materials. These bodies ai 

 the cessation of life cannot be utilized 

 directly as food by any of the higlier 

 plants and by but few animals. If the 

 action of the bacteria of putrefaction 

 were not present we should soon have 

 practically all the available food ma- 

 terials in the universe bound up in 

 these dead bodies, and after a time all 

 life must cease, because there would 

 be no food substances with which life 

 may be supported. But the bacteria 

 of putrefaction live by means of these 

 dead bodies and in so doing break up 

 their compounds, which soon become 

 scattered into the air and soil. Some 

 of these decomposition compounds 

 may be used directly by higher plants; 

 and some of them, having too much 

 nitrogen in proportion to the amount 

 of oxygen contained are further acted 

 upon by the nitrifying bacteria and 

 made into nitrates which contain 

 enough oxygen to make them suitable 

 foods for higher plants. It is clear 

 then that these two groups of bacteria 

 —the putrefactive and nitrifying— con- 

 stitute connecting links in nature's 

 food cycle. By means of their action 

 food substances may be used again and 

 again, first by plants, then by animals, 

 and so on so long as there are present 

 the organisms and energy which make 

 the transfer from one to the other. 



