42 ELIOT P.. CLARK 



Roux, in his later writings, discusses, mainly in a theoretical 

 way, the factors involved in the increase in size of vessels, and 

 the new formation of capillaries. His views as to the new forma- 

 tion of capillaries, expressed briefly in 1895, repeated more fully 

 in 1910, and again repeated, in a controversial article in 1911, 

 are perhaps most completely expressed in 1910, p. 88, where he 

 says: 



1st der Verbrauch in dem Parenchym, welches cine Kapillare um- 

 gibt, eiiiige Zeit dauernd derartig gesteigert, dass aiis den vorstehend 

 erorterten Griinden mehr Stoff als normal liindurchtritt, so wird wohl 

 die an der Stelle stiirksten Durchtritts gelegene Wandungszelle diirch 

 die verstarkte Leistimg in der Richtung des Austritts zur Sprossimg 

 angeregt. Dasselbe geschieht natlirlich auch an der denselben gros- 

 seren Parenchj'mtheil von der andern Seite der umschliessenden und 

 ernahrenden Kapillare. Diese noch nicht als Kapillarenfungierenden 

 sprossen treffen, Avohl diii'ch chemotropisch vermittelten Cjd^otropism, 

 aiifeinander, also in ahnlicher Weise wie ich es an von mir isolirten 

 Furchungszellen sah, einerlei ob diese Zellen noch freilagen oder schon 

 wieder an etwas anderem (an der Zellen oder am Boden des Gefasses) 

 hafteten. Der vererbte gestaltende Reaktionsmechanismus der Ka- 

 pillarwand, der zum Hohlwerden und zur weiteren Ausbildung der 

 neuen Kapillaren mit Bildung von Nerven und kontraktilen Elementen 

 fiihrt, wird auf diese Weise aktiviert und so eine neue funktionsfabing 

 KapiUare gebildet. 



Like Thoma, Roux considers the metabolism of the tissue the 

 primarj^ factor in new growth of capillaries. As for the specific 

 stimulus, however, he disagrees. According to Thoma, increased 

 metabolism causes increase in blood pressure in the capillary 

 area, to which the endothelium is thought to respond by sending 

 out sprouts, while Roux' view is that the new sprout is sent out 

 as a direct response on the part of the endothelial cell to the 

 passage through it of an increased amount of substances. In 

 criticism of Thoma's hypothesis, Roux ('11, p. 201) calls atten- 

 tion to the absence of any noticeable new formation of capillar- 

 ies in tricuspid or mitral insufficiency, in which conditions there 

 is a rise in blood-pressure in the capillaries. 



Thoma's first histomechanical law that the size of the vessel 

 is regulated by the rate of blood flow, is criticized by Roux 

 chiefly because he can see no way in which the moving stream 

 can affect the wall, since, as first shown by Helmholtz, there is 



