750 FRANCIS H. McCRUDDEN 



"Nature adopts a different method in effecting the absorption of bone. The salts 

 are not first extracted and the ground substance afterwards absorbed. Wherever bone 

 disappears, Howship's lacuna? are at once formed and filled with osteoclastic giant 

 cells. The minuti* of the process of bone resorption are indeed still completely un- 

 known to us, but it is certain that at no stage does an osteoid tissue free from lime 

 occur." 



(P. 633.) "The osteogenic zones . . . must have originated solely by apposition. 

 That the bones are for a long time certainly till the age of vigorous manhood the 

 subjects of an uninterrupted and coincident apposition and resorption, from which even 

 the interior of the compact ground substance is not exempt, is a thoroughly established 

 fact. The distinctive criterion of oeteomalacia would accordingly be the apposition of 

 ground-substance, free from earthy salts, i.e., of osteoid tissue, instead of normal 

 osseous material. It appears then, that rickets and true osteomalacia are very closely 

 allied diseases, since both depend on the apposition of an osteogenic substance free 

 from lime in place of typical osseous tissue. We may, in fact, dispense with a dis- 

 cussion of the many points of dissimilarity, inasmuch as these may be inferred from 

 the difference of the ages of the individuals affected, i.e., from the state of development 

 of the skeleton." 



Langendorff and Mommsen, who were studying osteomalacia at 

 the time Cohnheim wrote, were struck by the great similarity of the 

 bone in their case of osteomalacia to new osteoid tissue, and suggested that 

 in their case, and, perhaps, in some other cases, Cohnheim's hypothesis 

 might apply. But otherwise Cohnheim's hypothesis seems to have made 

 little impression. 



In 1891 Recklinghausen(&), in an exhaustive report on the his- 

 tology of osteomalacia and similar conditions, called attention to the 

 abundance of osteoblasts and Sharpey's fibers and to the "youthful ap- 

 pearance," as he calls it, of many of the bone corpuscles as evidence that 

 the osteoid tissue is new tissue. He refers to the fact that patients with 

 osteomalacia often start a good callus formation. In an elaborate account 

 of a continuation of this work, published in two large volumes in 1910 

 (Recklinghausen(c)), and containing rontgenographs, as well as histolog- 

 ical studies of all conditions at all similar to osteomalacia, von Reckling- 

 hausen completely confirms his earlier views and retracts certain doubts 

 expressed in his earlier paper. He states definitely that rickets, osteo- 

 porosis, and osteomalacia cannot be differentiated morphologically. 



Other investigators have confirmed the findings of von Recklinghausen 

 (Looser(a), Axhausen, also Gayet and Bonnet). Meek has pointed out 

 that certain spicules of bone in osteomalacia are in process of absorption, 

 as shown by the presence of osteoclasts lying in the lacunae at their edges; 

 other spicules are surrounded by closely applied osteoblasts, and evidently 

 consist of newly formed bone in which calcification has failed. And 

 Tashiro has pointed out that there is abundant newly formed osteoid tissue 

 which can be distinguished from the old decalcified tissue (of which there 

 appears to be some) by being not in layers, but contiguous to, and con- 

 tinuous with young proliferating endosteum ; this tissue contains an 

 abundance of osteoblasts. 



Hanau's finding of histological changes similar to those in osteo- 

 malacia, at postmortem examinations of the bones, especially the pelvic 



