CHAP. VII.] THE CONNECTIVE TISSUES. 283 



others by cutting off the salts of lime more or less completely 

 (Letellier, von Bibra, Chossat, Milrie Edwards 1 ), whilst not a few have 

 found that although the animals subjected to these conditions suffered 

 in health and even died, they shewed no symptoms of rickets (Leon 

 Tripier 2 , Weiske 3 ). We think, from a careful perusal of the experi- 

 mental evidence bearing on this question, that we may draw from 

 it the following conclusion. When young animals are subjected 

 to an insufficient diet or one in which certain of the alimentary con- 

 stituents are deficient, there is engendered a predisposition to rickets, 

 although there is no evidence to shew that such insufficient or improper 

 diet can, acting alone, induce the disease. 



Amongst the views which have been promulgated and adopted by 

 eminent writers on this subject is that which ascribes the chief part 

 in the production of the disease to the formation of lactic acid in the 

 alimentary canal ; the acid thus formed is supposed to be absorbed 

 into the blood and to act ' as an irritant on the osteoplastic tissues' 

 and 'as a solvent on the calcareous salts deposited in the bones, 

 promoting their elimination 4 .' 



This theory rests upon the most unsatisfactory evidence, as, that 

 the amount of lime excreted in rickets is increased (a fact which 

 has not been established by one single properly conducted observation) : 

 that rachitic bones have been found to contain lactic acid after death : 

 and that the urine of rachitic children contains lactates. 



Even assuming that large quantities of lactic acid were generated 

 in the alimentary canal these would necessarily be converted into 

 lactates in the blood. No one has been bold enough to assume 

 that in rickets, or any other disease, the blood loses its alkaline reac- 

 tion, for no one could conceive of an acid reaction of the blood being 

 compatible with a prolonged continuance of its functions ; and yet 

 in order that lactic acid could exert any solvent action, it would 

 be necessary that it should exist in a free condition in the blood 

 or that, by an unknown chemical decomposition, alkaline lactates 

 should be decomposed in the bones. This theory like all crude 



1 Amongst more recent researches which confirm the older writers on the possibility 

 of inducing rachitis by a diet poor in lime salts are those of T. Lehmann, " Ueber den 

 Einfluss der Nahrung auf die Knochenbildung." Abstracted in Maly's Jahresbericht, 

 Vol. vin. (1879) p. 272. 



2 Leon Tripier. See the admirable article referred to in note 3, p. 282. 



3 Weiske, "Einfluss Kalk- oder Phosphor saure armer Nahrung auf die Zusammen- 

 setzung der Knochen." Zeitschriftf. Biologie, Vol. vn. pp. 179 183 and pp. 333337. 



4 This view is adopted by Senator in his article on Kickets in Ziemssen's Cyclopaedia 

 of the Practice of Medicine, English edition. Vol. xvi. p. 178. We quote his very 

 words, " To sum up : the morbid process which underlies the development of rickets 

 may, in accordance with the results of experiments and the clinical observations we 

 possess, be explained in the following manner. Owing to digestive disturbance,, either 

 preexistent or brought on by improper feeding, lactic acid is generated in the system ; 

 this operates, on the one hand, as an irritant on the osteoplastic tissues ; on the other, 

 as a solvent on the calcareous salts deposited in the bones, promoting their elimination. 

 At the same time the supply of earthy matter is reduced, either directly (as in cases of 

 protracted lactation) or indirectly (as when diarrhoea carries off the lime-salts from the 

 intestines before they are absorbed)." 



