In accordance with what has just been said above, is an observation by Johannsen (St. Petersburg). He describes a case of venous thrombosis of the right arm and leg. The latter became gangrenous. At the amputation of the thigh several veins were found filled with firm thrombi extending far up, while the femoral artery had only some slight atheromatous degeneration.

Cases of thrombosis of the cerebral sinuses are also on record. Especially characteristic of influenza, although of rare occurrence, yet observed relatively frequently, is the occlusion of larger arteries by thrombi. It has also been occasionally observed in other infectious diseases, especially after typhoid, but is extremely rare*

Thrombosis as a complication was really first recognized in our recent pandemic, for, apart from a short note from the time of the epidemic of 1782 concerning "spontaneous gangrene of the extremities" following influenza, we do not know of any other mention in the early literature. Those from the recent epidemic are, however, extremely numerous. We would call attention to the reports of Senator and von Gerhardt (January 23, 1890), of von Leyden, Cam erer, Georg Sydenham, Loison, Cathomas, Emminghaus, Eichhorst, Bondet, Duchesneau, Teissier, Hugh-Highet, Stevensohn, Steinegger, Wartenweiler, Vonmoos, Keller; furthermore, the German collective investigation, the collection of the official German reports by P. Friedrich, and the Swiss report by Schmid.

The occlusion generally affects large arteries, and is relatively often bilateral, affecting symmetric vessels. The popliteal artery is the one most frequently occluded.

In the eight cases of the German collective investigation the popliteal artery was affected five times; the femoral, once; the brachial, once; and the cerebral arteries once. The cases of Keller, Stevensohn, Cathomas, as well as Leyden's second case, were of the brachial artery. Emminghaus described a rare case of endaortitis with thrombus formation in the ascending aorta. The cases of thrombosis of the splenic artery (report from Hessen) and of the mesenteric artery, with necrosis of the intestine (Stevensohn), were probably of an embolic nature.

The signs of arterial occlusion are the ordinary ones: generally, severe pain; always, absence of pulse and coldness and anesthesia_of the extremities; bluish black discoloration, then dry gangrene, with mummification of the affected part; marked prominence of the cutaneous veins. If the thrombosis affects an easily palpable artery (popliteal, femoral, brachial), the thrombus can be recognized as a tough strand. The prognosis is naturally a very unfavorable one; even in amputated cases, death almost always follows. The arterial thrombosis frequently gives rise to autointoxication, which is caused by the absorption of katabolic poisons. There are the facial expression and color of the skin of septicemia, collapse, generally with hypothermia and great cardiac weakness, total anorexia, and delirium.

* Compare the instructive article by von Leyden concerning arterial thrombosis' after the acute infectious diseases, "Berlin, klin. Wochenschr.," 1890, 14.

The cause and etiology of the arterial occlusion following influenza are undoubtedly manifold.

Teissier and the French physicians speak simply of an " arterite grippale," similar to their "arterite typhoidique," applied to gangrene following typhoid, without entering upon any explanation of the process.

In a number of cases there may have been emboli, especially in those where arteriosclerosis of the aorta existed, together with acute or chronic endocarditis; and even in cases where gross pathologic changes could not be found or detected, thrombi may have become detached from the left heart.

Occasionally influenza may have been directly followed by senile gangrene, or influenza may have accelerated an arterial occlusion already prepared by an arteritis obliterans by its enfeebling effect upon the heart.

But even conceding all these possibilities, there still remain a large number of cases which can be explained only as cases of primary or spontaneous arterial thrombosis.

Von Leyden is disposed to connect the thrombosis with "the disintegration of the leukocytes, which are increased in number from the beginning of the disease up to and even after the fever crisis, and then give rise to much degenerative product." If these products of disintegration and the blood platelets become deposited in large quantity on the arterial wall, they may give rise to the formation of an arterial thrombus. Von Leyden calls attention to the analogous formation of thrombi of blood plaques in phosphorus, arsenic, and potassium chlorate poisoning; and the gangrene following carbon monoxid poisoning might also have been mentioned here.

Gerhardt, who observed a case of bilateral occlusion of the crural artery followed by gangrene of the toes on one side and the lower third of the leg on the other, is disposed to class such cases together with "symmetric gangrene," and believes that it is a spasmodic vascular contraction and "vasomotor gangrene," since there were in his case certain visual disturbances similar to those occurring in symmetric gangrene and dependent on spasm of the retinal arteries. But the symptom complex of "symmetric gangrene" in the strict sense of the term is very definite. There is spasm only of the smallest arterioles, and the extremely slow progress of the dry gangrene remains confined to the tips of the toes and the terminal phalanges, and hardly ever spreads to the tissues higher up. Such a typical case following influenza has been recorded by Hugh-Highet in a girl twenty years of age, in whom the gangrene remained exclusively confined to the symmetric toes and terminated in recovery. The case of Petrina may be due to a similar condition of vascular spasm; this author observed alternating sensations of cold and warmth in one finger and one toe after influenza. I found in the literature but one case of typical "symmetric asphyxia" (Raynaud) occurring after influenza. It was reported by Le Joubioux, and occurred in a woman of thirty five.

Regarding the condition of the blood in influenza, there are but few observations, and these by no means exhaustive.