344: ANNUAL OF SCIENTIFIC DISCOVERY. 



organisms which have no permanent mouth. Some of these have the power 

 of forming a temporary sac for the purposes of digestion. 



Chemistry had from lime to time offered its aid to the naturalist. At one 

 time the possession of cellulose by the vegetable kingdom was considered dis- 

 tinctive, and the ready application of iodine and sulphuric acid as the test of 

 its presence rendered it an easily ascertainable diagnostic mark. Cellulose 

 has, however, been detected in some species of moUusca and in the brain and 

 spleen of man. Chlorophyll also appeared at one time to pronounce the 

 presence of plants; but this has been found in animal organisms. Starch 

 was another vegetable product easily detected by iodine, whose universal 

 presence in the plant seemed to olTer the best practical chemical test ; but 

 starch has been detected in the brain of man, and there is reason to suppose 

 it might be very generally present in the animal kingdom. It was thus 

 seen that no one point in structure or chemical composition could furnish a 

 means of distinction. A physiological point of much interest and importance 

 had principally determined a certain number of botanists in claiming the Di- 

 alomaceaj and Dosmidetc as plants. In certain Conferoe it had been ob- 

 served that previous to the production of the zoospore two contiguous cells 

 united, and each contributed its contents to form the germinating spore. 



Whatever might be the difficulties presented in any individual case, in the 

 application of any or all of the before-mentioned distinctions, there was evi- 

 dently a great antagonism or polarity exhibited by the animal and vegetable 

 kingdoms, viewed as a whole. They were mutually dependent, attained 

 the same end in their growth and organization, but by contrary means. The 

 great function of the animal tissues was the absorption of oxygen and the 

 disengagement of carbonic acid. The great function of the vegetable tissues 

 was the absorption of carbonic acid and the disengagement of oxygen. The 

 processes in the history of the life of the two kingdoms in which these dis- 

 tinctive functions appeared to be reversed, were not exceptions to the law, 

 but were due to other agencies than those connected with the essential life 

 of the plant or animal. Thus, carbonic acid was given out by plants at 

 night during fructification and germination. In the first instance, the gas 

 given out was that which has been taken up during the clay, and was not 

 decomposed by the agency of light. In the latter instance, a process of exu- 

 dation took place, in which the contents of the cells were undergoing change 

 independent of the life of the plant. The germ, during the growth of its 

 cells, absorbed carbonic acid and gave out oxygen, as in the growth of all 

 other vegetable cells. The development of the carbonic acid arose from the 

 decomposition of the starch and sugar of the albumen of the seed. In cases 

 where animals had been found to give off oxygen, it was doubtful as to 

 whether plants were not present, or even mistaken for animalcules. Atten- 

 tion was drawn to the fact that in all cases vegetable compounds are formed 

 from carbonic acid and water, or from carbonic acid, water and ammonia, by 

 the loss of oxygen. Acetic acid was referred to as an exceptional instance ; 

 but it was shown that it was more probable, where acetic acid occurred as 

 the result of vegetation, that it occurred as a result of dcoxydation than of a 

 process of fermentation in which alcohol was developed and subsequently 



