CATALYZERS OF GROWTH 511 



graph, but one-eighth of the animals so treated actually attained weights 

 in excess of forty grams, a weight which, it may be stated, no normal 

 female mouse ever attains. This remarkable overgrowth is probably 

 attributable to the preceding development of parenchymatous tissues. 

 The removal of the stimulus which enabled them to predominate in 

 the struggle for nutrients gives the sclerous tissues the opportunity 

 to develop, and the reattainment of normal proportionality between 

 the sclerenchyma and parenchyma finally enables the stimulation of 

 growth which has actually occurred to find expression in the super- 

 normal weight of the animal as a whole. The occurrence of Acromegaly 

 in man may actually indicate therefore, not a present hyperactivity of 

 the hypophysis, but a preceding hyperactivity, succeeded, before the 

 onset of the acromegalic symptoms, by a normal or even subnormal 

 activity of the gland. 



It is a noteworthy fact that although the administration of Choles- 

 terol or Tethelin to normal animals which have been inoculated with 

 Carcinoma leads to acceleration of the growth of the neoplasm, yet it 

 has so far proved impossible, despite many trials, to induce the spon- 

 taneous development of tumors in animals by the administration of 

 these substances. The percentage of mice which develop carcinoma 

 is the same in animals which have received cholesterol or tethelin for 

 the greater part of their lives as it is in normal animals. In other 

 words these substances, like the catalyzers with which we are familiar 

 in other chemical transformations, are unable to initiate the reaction 

 which they accelerate. 1 Moreover the spontaneous development of 

 carcinoma is even greatly delayed and the growth of the neoplasm 

 when it has arisen is very much slowed by the continuous administra- 

 tion of tethelin to animals. It would appear that the continuous 

 administration of tethelin results in such a disproportionate develop- 

 ment of parenchymatous tissues that they are enabled to compete 

 successfully with the neoplasm for the nutrients in the tissue-fluids, 

 whereas in the normal animal the neoplasm shares with the limited 

 proportion of parenchyma the advantages of enhanced catalysis of the 

 growth-processes. 



Carcinoma is essentially a disease of old age and the investigations 

 of Wacker have shown that the cholesterol-content of the subcutaneous 

 fats is exceptionally high in elderly people and in persons afflicted with 

 carcinoma. Luden has also found that cholesterol is exceptionally 

 abundant in the blood of individuals suffering from carcinoma, w r hile 

 the oxidation-products of cholesterol which yield Lifschiitz's reac- 

 tion without preliminary treatment with oxidizing-agents, which are 

 abundant in normal blood, are absent or scanty in the blood of carci- 

 nomatous individuals. 



1 Erdmarm has described an innoculable tumor which was produced by the inocu- 

 lation of foreign non-malignant tissue followed by an induced inflammatory reaction 

 ; u H! administration of tethelin, but. tethelin ajqne was ineffective. 



