Januaey 27, 1911] 



SCIENCE 



137 



THE EXISTENCE OF FORMALDEHYDE IN 

 PLANTS 



As an immediate result of Baeyer's 

 hypothesis attempts have been made to de- 

 tect formaldehyde in plants of various 

 species and grown under various condi- 

 tions. The results of these investigations 

 are not at all satisfactory and indeed con- 

 sist largely in affirmations and denials. 

 The problem, however, is not a simple one. 

 In the first place formaldehyde, if present 

 at all, can only be present in very minute 

 quantities because of its very great toxicity, 

 and while it is true that extremely delicate 

 tests have been advanced for formaldehyde 

 it is likewise true that these tests have 

 been subjected to considerable criticism. 

 Moreover, it is possible that such delicate 

 tests might be iniluenced by the presence 

 of various other substances present in the 

 plant. 



In 1881 Loew and Bokorny-^ advanced 

 the theory that the vital force of the living 

 protoplasm is essentially connected with 

 the presence of aldehyde groups in the 

 substance forming the protoplasm. When 

 certain algffi, for example, were immersed 

 in a dilute solution of silver nitrate the 

 living cells were found to be darkened 

 when examined under the microscope. 

 The authors attribute this change in color 

 to the reduction of the silver salt by the 

 aldehyde present. Plants previously im- 

 mersed in boiling water to destroy the life 

 of the protoplasm failed to give the test; 

 hence the authors conclude that the alde- 

 hyde group disappears with the life of the 

 plant. 



In the same year Reinke^^ by macerating 

 certain green leaves (those of the grape 

 vine, the poplar, the willow and conifers, 

 were tested) and distilling the mass in a 

 current of steam obtained a liquid having 



''Arch. ges. Physiol. (PflUgers) , 25, p. 150. 



^Ber. d. chem. Gesell., 14, p. 2144. 



strong reducing powers which he attrib- 

 uted to the presence of an aldehyde. 

 Moreover, the aldehyde must be an easily 

 volatile one, for it is present chiefly in the 

 first portions of the distillate. While not 

 able to prove the exact identity of the 

 aldehyde Reinke concluded that it is 

 formaldehyde. These reactions were ob- 

 tained only in the ease of chlorophyll- 

 bearing plants. Reinke suggested that the 

 reducing power of the algse observed by 

 Loew and Bokorny might be due to the 

 presence of formaldehyde in the plant. 

 This statement led to further studies by 

 both investigators and the publication of 

 several articles'^ in which each held to his 

 original interpretation of the results, al- 

 though Reinke was forced to admit that he 

 had not definitely proved the presence of 

 formaldehyde in the distillate from the 

 plants, but only the presence of an easily 

 volatile aldehyde. 



Mori^" (1882) experimenting with the 

 leaves of the rose bush and of oats ob- 

 tained results similar to those of Reinke. 

 He also tested the plant by adding a few 

 drops of SchifE's reagent directly to por- 

 tions of the plant, whereupon a red color 

 gradually resulted. Loew and Bokorny^^ 

 claim, however, that the development of 

 the color in Mori's experiments was due to 

 the evaporation of the sulphurous acid in 

 Schiff 's reagent and show that this reagent 

 gradually becomes colored by mere ex- 

 posure to air. 



In 1889 Polaeci^^ reported the results of 

 an extended series of investigations from 



''Bot. Zeit., 1882, No. 40; Ber. d. lot. Gesell., 

 15, p. 201; 17, p. 7; Ber. d. chem. Gesell., 15, pp. 

 107, 695 ; " Studien liber das Protoplasma," zweite 

 Folge, Berlin, 1883. 



"•Nuovo. Gio. Bot. Ital., 14, p. 147. 



^Bot. Zeit., 1882, p. 832; Arch. ges. Physiol. 

 {PflUgers), 26, p. 50. 



"Atti d. Inst. Bot. d. Univ. d. Pavia, II., Serie 

 7, 1. 



