410 



SCIENCE 



[N. S. Vol. XL VI. No. 1191 



tolic, the vessel is already completely filled, and 

 being inextensible, can not expand further and 

 therefore can not transmit the increase of inside 

 or arterial pressure when it rises above the dias- 

 tolic level. But I [Bleile] wish here to point out 

 that if the pressure in the chamber is at the dias- 

 tolic level and the pressure within the artery is 

 also just at the diastolic level, then it does not at 

 all follow that the artery must necessarily be 

 filled with fluid. Since the artery is readily col- 

 lapsible (though not elastic) it may be only partly 

 filled, or it may be entirely flat and empty. It 

 may be in any degree of fulness or emptiness. 

 But one must know the amount of fluid within the 

 artery before he can tell whether a rise in arterial 

 pressure will be transmitted to the chamber. As 

 a matter of fact, not unless the artery is com- 

 pletely filled with fluid at the diastolic pressure 

 and the chamber pressure just equal to it is applied 

 without allowing the artery to collapse the slight- 

 est amount, can the result obtained by Erlanger 



In order to bring clearly before the reader 

 tbe three sets of conditions described in the 

 foregoing quoted paragraph, I analyze them 

 here into the form of a table. In this table 



the numbers indicate the sequence of events. 

 It thus is made obvious that Dr. Bleile's 

 second set of conditions is merely a repetition 

 of mine. And he admits that under his second 

 set of conditions there will be no oscillations, 

 which, it will be noted, is exactly the conclu- 

 sion I came to. This result can be altered 

 only by supplying energy not included in my 

 premises. To be sure, no one can find any 

 fault with the conclusion Dr. Bleile is led to 

 by his first set of conditions, but they are not 

 the set of conditions I chose to start with in 



developing the theory of compression oscilla- 

 tions. Joseph Erlanger 

 Washington Univeesity Medical School, 

 St. Louis 



the correct name for our apple-grain 



APHIS 



Much confusion has existed in regard to the 

 name applied to our apple-grain aphis. In the 

 first place the name avence which is now ap- 

 plied to this species in America was for many 

 years applied to Macrosiphum granaria. These 

 two species were eventually separated and 

 granaria applied to the Macrosiphum on grains 

 and grasses and the name avence restricted to 

 the present species or group of species on the 

 same plants. 



To the apple-grain aphis on its primary host 

 the name mali Fab. was applied. This name, 

 mali, is, however, a synonym of pomi DeGeer, 

 a species which was not well known in Amer- 

 ica. The alternation between grains and apple 

 was worked out while the name mali was still 

 in use for the species. When pomi became 

 better known it was shown that the present 

 species was not mali, i. e., pomi, but was in 

 reality the same species as the so-called avenm 

 on grains. Pomi was then restricted to the 

 true pomi and avenm transferred also to the 

 apple-feeding form of this grain aphid. 



Fitch described a species under the name 

 prunifolice which he found upon the plum. In 

 this description he gave the characters of some 

 specimens collected and placed in his cabinet. 

 These specimens are now in the National Mu- 

 seum collection and show that the species he 

 had was the one treated in this note. Before 

 publication, however, he observed some other 

 specimens on plum and these had a black spot 

 on the abdomen. He therefore included in his 

 description remarks on this spot. His speci- 

 mens, however, show that he really had the 

 apple-grain aphis in his collection and in his 

 manuscripts as prunifolice. 



On account of his mentioning this spot sub- 

 sequent writers considered his specimens to be 

 specimens of pruni Koch. This latter species 

 has been shown to migrate to thistles and in 

 reality to be a synonym of cardui L. Therefore 

 recent writers have considered Fitch's pruni- 



