Febkuaky 23, 1917] 



SCIENCE 



193 



really hexagonal. The outline of the crystal plate 

 then comes to be bounded by curved (not straight) 

 lines which show the hexagonal angles at the place 

 where this average adjustment is most perfect. 

 This curving of the bounding outlines renders the 

 measurements variable and these measurements I 

 regard as untrustworthy. The true hexagonal 

 angle is 60° or 120° and the pseudo-hexagonal (but 

 reaUy monoclinic) angle may be 123° or 124° or 

 its supplement and the influence of this produces 

 its curving. Examples of such curving outlines to 

 these crystals produced by this sort of twinning 

 may be seen in Eeiehert and Brown "Crystallog- 

 raphy of Hemoglobin, etc.," on Plate 3, Pigs. 14 

 and 18, and Plate 4, Fig. 19, and the "regular 

 growth" of the methemoglobin (hexagonal) over 

 the oxyhemoglobin crystals (monoclinic but pseudo- 

 hexagonal) which sufiSeiently approaches the true 

 hexagonal angles of the methemoglobin to enter 

 into regular growth with this substance is illus- 

 trated on Plate 4 in Figs. 20-23 in the case of 

 shad blood. It is this pseudo-symmetry which 

 renders the measurements of such twinned crystals 

 imeertain and inconstant. Fortunately this difii- 

 eulty does not apply in the case of the orthorhom- 

 bic crystals of the bloods under consideration, 

 nor indeed in the case of the majority of ortho- 

 rhombic crystals, although this tendency to 

 mimetic twinning must always be borne in mind. 

 I do not think it need be considered in the case of 

 the orthorhombic crystals of either the donkey, 

 horse or mule, which are the animals under con- 

 sideration. But the measurements of the ■mono- 

 clinic crystals from the blood of these three ani- 

 mals are rendered uncertain and are made variable 

 by this tendency to mimetic twinning. Therefore 

 it is to the orthorhombic crystals that I must turn 

 to formulate any conclusions as to the likenesses or 

 the differences in these bloods. Fortunately in the 

 imoxalated blood that you sent me the production 

 of crystals is easy, and, while their measurement 

 is not easy, I think that you may rely upon the 

 results obtained; at least they are as reliable as I 

 can make them with my present methods. The 

 results from these orthorhombic crystals as com- 

 pared with those of horse and mule are given be- 

 low. 



Horse.... 

 Donkey. 

 Mule^... 



0.7467:1:0.4097 

 0.7522:1:0.4144 

 0.7813:1 : 0.4198 



Angle 

 (Normals) 



73° 30' 

 73° 54' 

 76° 00' 



Macrodome 



Angle 

 (Normals) 



57° 30' 

 57° 42' 

 56° 30' 



These measurements appear to indicate, as I said 



at first in this letter, that the crystals of "a-oxy- 



hemoglobin ' ' of the donkey approach more nearly 



those of the horse than they do those of the mule. 



Very sincerely yours, 



(Signed) Amos P. Brown 



It is impossible to utilize these results for 

 or against the idea tliat species-specificity is 

 a Mendelian character. In view of the bear- 

 ing on the problem of the inheritance of spe- 

 cies-specificity the writer thought that even 

 these negative results might be of some in- 

 terest. 



A further difficulty which besets the solution 

 of this problem is that the terms species and 

 genus are selected on a morphological basis 

 and not according to the protein reactions in- 

 volved in the phenomena of species-specificity. 



Jacques Loeb 



The Eockefelleb Institute 

 POK Medical Eeseakch, 

 New York 



3 Donkey ^J and horse 5- 



THE AMERICAN PHYSICAL SOCIETY 



The eighty-sixth meeting of the American Phys- 

 ical Society was held at Columbia University, De- 

 cember 26-29, 1916. Sessions on Tuesday after- 

 noon, Thursday forenoon and afternoon, and Fri- 

 day forenoon and afternoon were joint sessions 

 with Section B, American Association for the Ad- 

 vancement of Science, and were held at the School 

 of Journalism. The two sessions on Wednesday 

 were joint sessions with Sections B and C and were 

 held in Havemeyer Hall. The following program 

 of papers was presented: 



A Proposed New Form of Seismograph. Her- 

 bert BeU. 



The Velocity of Sound in Gases in Metal Tubes, 

 as a Function of Density. Karl K. Darrow. 



Measurements in Frictional Electricity. L. E. 

 Woodman and N. E. French. 



The Preparation of Metallic Mirrors, Trans- 

 parent Metallic Prisms and Films by Distillation. 

 Otto Stuhlman, Jr. 



Our Part in the Advancement of World Physical 

 Science. L. A. Bauer. 



Some Experiments Concerning Magnet-Photog- 

 raphy. L. A. Bauer and W. F. G-. Swann. 



