MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 283 



elusion that etiolation is not necessarily a pathological condition, a 

 statement corroborated by the condition of the protoplasts of the 

 organs in question. As pointed out previously, both increase in size 

 and multiplication of elements ensues in etiolated organs, and his 

 generalization upon this subject becomes worthless in the light of 

 extended observations. The stems of climbing plants have been 

 shown by myself to be not " naturally etiolated " but to owe their 

 behavior in darkness to other and more direct physiological causes. 

 The failure of the greater number of the conclusions of Sachs to 

 stand the test of modern observations must be taken to rest upon the 

 fact that his experimental evidence was obtained chiefly by " partial 

 etiolations " and to the growth of plants under conditions in which 

 the action of light was imperfectly excluded. The assertions of 

 Sachs as to the necessity for special formative materials, and the 

 action of the ultra-violet rays as to the retarding influence of light 

 upon growth will be taken up in the following pages. 



Batalin (1869, 1871) set himself against the " self-nutrition " the- 

 ory advanced by Kraus in explanation of the non-development of 

 leaves and other etiolated organs, and attributed their atrophy to the 

 incapacity of the plant to carry on cell-division in the shoot in the ab- 

 sence of light, the rays supposedly exerting a direct influence upon 

 the tissues (pp. 11, 12) in normal shoots. Rauwenhoff (1878) also 

 held that the abnormal condition of leaves in darkness was partly 

 pathological, and that the characteristic positions of etiolated organs 

 were due to geotropic reactions unhindered by phototropism, and mod- 

 ified to some extent by the unusual conditions of the tissues. The 

 interpretation of etiolation as a direct adaptation, and the assumption 

 that the attenuation, or elongation of axial organs as a means of lift- 

 ing chlorophyl-be^ring surfaces past a theoretical obstruction, seems 

 to have originated with Boehm in 1886, although not elaborated 

 until taken up by Godlewsky in 1889 (p. 20). The formulation of 

 this theory may be taken to mark a distinct advance in the investi- 

 gation of the subject, and various modifications and applications 

 have been made of its corollaries by several workers. It is notable 

 that Frank (p. 24) attributed the behavior of the plant in darkness to 

 an adaptive reaction on the part of the plant, and asserted that light 

 and darkness exert a direct stimulative effect upon plants, the various 

 organs of which react in a characteristic manner, and that he was not 

 aware that such an explanation had been previously offered (Lehrbuch 



