Charles-Sedgwick Minot 253 



example, the liver and Wolffian body, cannot be understood or even 

 described correctly without taking into consideration the sinusoidal 

 character of their circulation. In this case also, the adoption of the 

 genetic interpretation is much needed. We shall apply presently the 

 concept " sinusoid '■' to aid us in the interpretation of glands. 



We may pass now from a consideration of tissues to that of organs, 

 and begin with the glands. The classification, which at the present time 

 prevails vfidely, is one based upon certain incidental peculiarities in the 

 shape of the secretory portion of the glands, so that they are put into two 

 main divisions : the tubular and alveolar; then under each of these we 

 have three main parallel groups : 



the simple tubular or alveolar glands; 



the simple branched tubular or alveolar glands ; 



the compound branched tubular or alveolar glands. 



But in this classification there is no place for such a gland as the liver 

 and the thyroid. In text-books of histology, we find the liver tucked in 

 under the tubular glands and designated as a reticulated tubular gland, 

 and the thyroid placed as a follicular gland under the head of the alveolar. 

 But in another way the system also fails, for there are tubulo-alveolar 

 glands which again must be classified as simple, simple branched, or 

 compound branched. Essentially this classification is adopted by the 

 authors of the manuals of histology which I have examined. To classify 

 glands thus, seems to me about on a par with classifying organs by their 

 being solid or hollow, a principle, which would put the spinal cord in the 

 same class with the intestine, and nerves in the same class with the 

 tendons. The peculiarities of shape of the secretary portions of glands 

 are entirely secondary, and do not indicate anything fundamental in 

 regard to the structure of the gland itself. We cannot call a system good 

 which, if applied in accordance with its own definitions, would put some 

 of the mucous glands of the stomach in one division, others in another 

 division, because, although these glands are alike in their histological 

 structure, some of them are branched and some are not. Must we not 

 condemn a view, which excludes the ovary from the glands and makes 

 the testis a compound tubular gland, although ovary and testis are strictly 

 homologous organs, even in the details of their structure? These are 

 only samples of the innumerable difficulties which the system encounters, 

 -because it is essentially pedantic, admirable as an orderly arrangement of 

 names, but impossible as a presentation of anatomical facts. 



It appears to me not difficult to make an entirely new classification of 

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