236 William Christopher Kraiiss 



defects are the result probably ot some constriction or pressure 

 from folds or bands of the foetal membranes, or by loops of the 

 umbilical cord. Cases of this kind are by no means rare but 

 have been carefully studied by Foerster, Voight, Gruber and 

 others. The different classes are distinguished according to 

 the degree of malformation as follows : 



(i) Amelus. lyimbs entirely wanting or replaced by wart- 

 like stumps. 



(2) Peromelus. All four extremities stunted. 



(3) Phocomelus. lyimbs consisting merely of hands and 

 feet sessile upon the shoulders and pelvis. 



(4) Micromelus. Limbs regular in form but abnormally 

 small. 



(5) Abracliius and Apus. Absence of upper limbs, while 

 the lower are well formed, and vice versa. 



(6) Perobrachius and Peropus. Arms and thighs normal ; 

 forearms and hands, legs and feet malformed. 



(7) Monobrachius and Monopus. Absence of a single upper 

 or lower limb. 



(8) Sympus apus and Sympus opus. Absence of feet ; or 

 they may be represented by single toes, or by one foot as in 

 siren monsters. 



(9) Achirus and Perochirus. Absence or stunted growth 

 of the entire hand or foot. (Ziegler.) 



It is not the purpose of this paper to invade the field of ter- 

 atology, but to study another morbid process which also ends 

 in defect of structure, not, however, through interference of 

 growth, but through the destruction and degeneration of 

 muscles once able to perform work measured by their develop- 

 ment and vitality. This process is more properly termed re- 

 gression or retrogression, and the designation muscular 

 atrophy as commonly employed has reference only to a retro- 

 grade metamorphosis of a fully developed muscle. 



Inasmuch as there are atrophies due to physiological and 

 also others due to pathological processes it is of the utmost 

 importance to distinguish between them. Generally speak- 

 ing, physiological atrophy occurs as the result of the decadence 

 of the vital powers due to senile changes. It is not attribut- 



