162 THE BLOOD AND ITS CIRCULATION. 



These rapidly sketched histologies! details show that our 

 present ideas might easily change on the subject of the prop- 

 erties of the globules, especially their contractility: their 

 coats are composed of globules which have, no doubt, pre- 

 served the properties of the living globule : Strieker, indeed, 

 has no hesitation in pronouncing these coats contractile ; he 

 asserts that he has demonstrated that the capillary coats of 

 toads possess a contractility shown by alternate shrinking 

 and enlargement, and thus believes himself authorized in 

 attributing the same property to the capillaries of completely 

 developed animals. If this view is confirmed, it will not be 

 so necessary in future, in a physiological point of view, to 

 distinguish the capillaries properly so called, from the small 

 arteries and veins, and we may allow that there are several 

 varieties of capillaries. (See p. 160.) 



We will add, finally, that the investigations of Sucquet 

 and Pean show that the communication between the arterial 

 and the venous cone is sometimes made without the medium 

 of the capillaries, by means of small intermediate vessels, 

 visible to the naked eye, and abounding in muscular ele- 

 ments : it is asserted that these vessels sometimes contract, 

 but under other circumstances dilate, leaving an easy pas- 

 sage to the arterial blood, which flows directly into the 

 veins, the capillary circulation being reduced to its minimum, 

 whence the name of derivative circulation. This disposition, 

 which all anatomists have refused to admit until now (it is 

 denied by Vulpian) is found, according to Sucquet, especially 

 in the extremity of the fingers and toes, in the front of the 

 knee and the back of the elbow, in the skin of the lips, the 

 cheeks, the nose, the eyelids, the mucous membrane of 

 the nasal chambers and of the tongue. 



French schools: though rejected by Ch. Robin, it is- held without 

 any restriction by Vulpian and Charcot, who make it the basis of 

 their teaching on the subject of inflammation. We must add that, 

 in a course of experiments made personally, we have remarked the 

 passage of the white globules only under exceptional circumstances, 

 and when suppuration, which was already far advanced, had brought 

 the vascular coats back into the embryo state. (See Duval and 

 Strauss, " Archiv. de Physiol.," 1872.) Messrs. Feltz and Picot 

 have also published observations opposed to the theory of diapedesis 

 (" Journal de 1'Anatomie "of Ch. Robin, 1871-1878). 



See also a late monograph by Cohnheim, wherein he asserts the 

 true nature of inflammation is not yet discovered, the passage of 

 the globule being attributed to a secondary rather than a primary 

 cause of the pain, heat, and redness. 



