224 CRYSTALLOGRAPHY OF HEMOGLOBINS OF THE RODENTIA. 



The needles in the dense tufts show the oxyhemoglobin color, but individual needles 

 are very pale owing to their tenuity. Pleochroism is noticeable, the direction of the 

 length of the needles showing more color than the normal to the length. The elasticity 

 is greater normal to the length of the fiber and less parallel to the length. They are so 

 thin that no characters can be made out in convergent light; but extinction is straight 

 in all aspects; and this, with the four-sided cross-section, reduces the possible crystal 

 systems to two, orthorhombic and tetragonal. The lozenge-shaped section indicates 

 that the crystallization is orthorhombic. The blood was examined before we had devel- 

 oped our methods of retarding crystallization in order to produce better crystals, and 

 hence this blood should be further investigated. 



GROUND-HOG OR WOODCHUCK, Marmota monax. Plates 49 and 50. 



Specimens of this animal were purchased at different times from 

 collectors in eastern and central Pennsylvania, and were bled in the lab- 

 oratory. The blood was collected in oxalate. The first preparations were 

 made by laking the oxalated corpuscles, and centrifugalizing, and from the 

 clear solution preparing the slides as usual. As these preparations produced 

 mainly long needles, that did not show the crystallographic characters 

 definitely, and as the hexagonal plates that finally appeared were so im- 

 perfect that better preparations seemed necessary, others were made, 

 using the whole blood, the preparations being made as above described. 

 In these preparations from the whole blood, the first crystallization in the 

 dried protein ring is in the form of minute hexagonal plates; these soon 

 become covered by the rapidly developing needles, and in part dissolve; 

 so that the slides finally contain only masses of the needles. A preliminary 

 trial of diluting with the blood plasma, and etherizing strongly before 

 centrifugalizing, proving satisfactory in developing the plates, preparations 

 were made by diluting the whole blood with an equal volume of the blood 

 plasma and laking, and carrying out the preparation as above described. 

 In this diluted blood, the plates developed readily and grew to large size, 

 with only a slight development of the rods. The hexagonal plates kept 

 well and passed by paramorphous change into reduced hemoglobin and also 

 into metoxyhemoglobin. The crystals at first formed were, in all cases, 

 oxyhemoglobin. Crystals form very readily in solutions of either the 

 corpuscles, the whole blood, or the whole blood diluted with plasma; but 

 much more rapidly, of course, in solutions of the corpuscles alone than in 

 the less concentrated solutions. The development of the needles, or of the 

 plates, can be controlled at will by the amount of dilution. The same 

 principle applies to other bloods that develop needles or hair-like crystals 

 from the whole blood. Unfortunately, however, the amount of blood in 

 the samples received was rarely enough to try the experiment, or the 

 plasma was not in good condition owing to putrescence. In rodents in 

 general, dilution of the blood by the plasma or serum will probably be 

 found advantageous. Two kinds of tabular crystals were observed in the 

 blood of the ground-hog; the one, hexagonal plates, that are probably 

 only pseudohexagonal and mimetic twins of the second kind, which latter 

 are in the form of rhombic plates, belonging to the monoclinic system. 

 These two will be described as a-oxyhemoglobin and y-oxyhemoglobin, 



