Adipocelluloses and Ciitocelluloses 231 



Fremy also made observations upon suberin (or suberose), 

 \vhich yielded similar products of saponification. He there- 

 fore concluded that the two products are substantially identical. 

 The products of oxidation by nitric acid are also indistinguish- 

 able, viz. chiefly suberic and succinic acids. 



These results suggest, from the purely chemical standpoint, 

 that the cellulose of the tissue and the waxy products of excre- 

 tion stand to one another in a genetic relationship, and the 

 cutose or suberose occupies an intermediate position. The 

 question of a direct conversion of cellulose into wax taking 

 place in these cuticular tissues was definitely raised and dis- 

 cussed by De Bary in his investigations of this group of plant 

 constituents (Bot. Ztg. 1871). It appears from these researches 

 that wax-alcohols are certainly not contained in the cell-sap or 

 protoplasm, and that their origin must be in the cuticular 

 tissues themselves ; but the parent substance may be either 

 cellulose, or some compound built up with it in the ordinary 

 course of elaboration. This question is left for the present 

 undetermined. It should be borne in mind, on the other hand, 

 that we have a great number of direct observations upon the 

 physiological equivalence of the carbohydrates and the fats, 

 both in the animal and vegetable worlds ; and although the 

 mechanism of the transformation of the one into the other 

 group of compounds remains unelucidated, it is after all not 

 more difficult to imagine than the condensation to furfural. It 

 is, however, not the purpose of this treatise to carry discussion 

 into purely speculative regions ; and it is sufficient to state the 

 conclusion that there is ample ground for adopting as a work- 

 ing hypothesis that carbohydrates, or possibly cellulose, are 

 transformed into cutose or suberose, and these, again, into free 

 waxy bodies of lower molecular weight, the whole process repre- 

 senting the change known as cuticularisation or suberisation. 



In all the researches above described there is no attempt to 



