April 30, 1897.] 



SCIENCE. 



683 



a tattered badge of pride to ourselves. 

 Here is a weapon, the use of -which has far- 

 reaching results that appeal to the imagina- 

 tion with the certain annihilation they in- 

 flict. Fellow-curators, grasp your weapon, 

 and, more powerful than Canute, force back 

 the advancing tide ! 



F. A. Bather. 

 British Museum (Nat. Hist.), 

 LoNDOJsr, S. W. 



INTERNAL SECRETIONS CONSIDERED IN RE- 

 LATION TO VARIATION AND DEVELOP- 



3IENT. 

 The so-called internal secretions of glands 

 and other organs consist of products manu- 

 factured by them and passed back to the 

 blood. Many of these products are known 

 to be of very great importance to the adult 

 organism ; it is possible that they may be 

 of no less importance to the developing 

 organism and that we may here find a clue 

 to some of the unsolved problems of devel- 

 opment. Internal secretions have probably 

 been longest recognized in case of the repro- 

 ductive organs. The effects of castration, 

 of non- development or development of these 

 organs are well kuown. It has also been 

 generally recognized that the influence of 

 these organs depends on substances formed 

 by them and given to the blood. What 

 these substances are is still unknown, but 

 there can be little doubt that their presence 

 determines the development of other organs 

 and characters, the so-called secondary 

 sexual characters. The long recognized 

 healing effect of removal of the ovary in 

 women suffering from soft bones and the 

 subsequent growth of bone and fatty tissue 

 has been the subject of researches by Cura- 

 tulo and Tarulli.* These authors concluded 

 that the ovaries produce a substance which 

 oxydizes the organic phosphorus com- 

 pounds and thus cause their rapid destruc- 

 tion. The removal of the ovaries would 

 seem to remove the destroying substance 

 *Phys. Cent. IX. 



and hence to cause a deposition of phos- 

 phorus, and experiment showed that after 

 extirpation of the ovary the excretion of 

 phosphorus fell off' one-half. 



Perhaps the best known internal secre- 

 tion is glycogen. This substance, made by 

 the liver and given to the blood, is used as 

 food by many other organs. Thanks to 

 Hedin, Minkowsky and others, the internal 

 secretion of the pancreas is now known to 

 be a necessity to the organism, for if this 

 organ is extirpated, the animal (mammal) 

 quickly dies from diabetes mellitus. What 

 the active substance is and whether it acts 

 directly on the liver or through the nervous 

 system is not yet decided. Equally impor- 

 tant internal secretions are produced by the 

 thyroid and thymus glands and the supra- 

 renal capsules, the complete extirpation of 

 any of which leads to rapid death, though 

 life may be prolonged for a longer or shorter 

 time by feeding the animal with the miss- 

 ing organ or injecting its extract into the 

 system. Very striking is the eflect of non- 

 development or over- development of the 

 thyroid on the cranium. The low broad 

 skull of the cretin forms a distinct type, 

 and the rapid change in physiognomy in 

 patients suifering from goitre after the re- 

 duction of the thyroid or the injection of 

 thyroidin is well known. According to 

 Brown-Sequard, the fatal results of extirpa- 

 tion of the kidney ai-e due not to poisoning 

 by urea, but to the lack of an internal 

 kidney-secretion essential in some' way to 

 the organism. There can be no doubt that 

 the muscles also form such a secretion, for 

 it has been shown that the excitation of the 

 breathing center on muscular activity is the 

 consequence of some chemical substance 

 given by the muscle to the blood. Perhaps 

 a similar secretion is the ammonia manu- 

 factured by the mucous membrane of the 

 stomach and carried to the liver, there to 

 be elaborated into other products. Al- 

 though such substances have not yet been 



