CHOICE OF METHODS XVU 



convolutions with so little injury that their behaviour in various experimental 

 conditions can be investigated (see also Clark, E. R., and Wentsler, N. E., Proc. 

 Assoc. Res. Nerv. and Ment. Dis., 1937, 18, 218-228). Through a window in 

 the thoracic wall Wearn and his associates (Weam, J. T. et al.. Am. J. Physiol., 

 1934, 109, 236-256) have similarly studied the pulmonary arterioles and capil- 

 laries. They employed a fused quartz cone to conduct light to the tissue. 



Other investigators have availed themselves of the natural window, the 

 cornea, through which what goes on immediately within it in the anterior cham- 

 ber of the eye can be observed. Several tissues have been successfully trans- 

 planted into this chamber. Perhaps the most dramatic is the behavior of trans- 

 planted uterine mucosa in the rhesus monkey. In it the menstrual changes 

 can be seen in detail and the influence of hormones noted (Markee, J. E., Con- 

 trib. to Embryol., Carnegie Inst, of Washington, 1940, 28, 219-308). For some 

 kinds of work the fact that the tissue fluid (aqueous humor) in this chamber 

 differs from others in the same animal by the absence of certain species specific 

 growth inhibiting factors is a priceless asset. Thus Greene (H. S. N., Science, 

 1938, 88, 357-358) was able to grow pieces of human cancers, which ordinarily 

 quickly die in other species, in the anterior chambers of the eyes of some mam- 

 mals. The existence of a barrier protecting this fluid against the entry of anti- 

 bodies from blood plasma and thus making possible the growth of tumor trans- 

 plants, while all other tissues are resistant to their growth, has recently been 

 emphasized (Saphir, O., Appel, M. and Strauss, H. A., Cancer Res., 1941, 1, 

 545-547). 



In order to view the less accessible living tissues, techniques have been devised 

 that include opening the body and partly withdrawing the organ so that it can 

 be placed on the stage of a microscope but with circulation and nerve supply 

 intact and adequate regulation of temperature and humidity. Particularly 

 fruitful has been the direct observation through oil immersion objectives of 

 secretion by acinous cells of the Pancreas by Co veil (W. P., Anat. Rec, 1928, 

 40, 213-223) and of islet cells by O'Leary, (J. L., Anat. Rec, 1930, 45, 27-58). 

 Thus the influence of drugs on the secretory process can now be followed in 

 minute detail. 



Knisely (M. H., Anat. Rec, 1936, 64, 499-523; 65, 23-50) has perfected a 

 technique for the study of the living Spleen at somewhat lower magnification. 

 The essential features are slight displacement of the spleen so that it can be 

 transilluminated by light delivered through a quartz rod. This allows for the 

 first time direct examination of the behavior of the venous sinuses. Undoubt- 

 edly the Quartz Rod technique will be of great service in providing light for 

 similar examination of other organs. 



3. To Study the Arrangement of Parts in the Body 



Since the body is structurally so very complex it is often illuminating to view 

 parts of it in their normal shape and size but unobscured by all the neighboring 

 components. There are several ways by which this can be accomplished. 



