320 



SCIENCE. 



[Vol. VII., No. 166 



periment which has of late attracted the most 

 attention has been the substitution of electricity 

 for steam on the New York elevated railways. 

 That this experiment has not succeeded as well as 

 could be wished is not due to any inapplicability 

 of electricity to the purposes of locomotion. All 

 that has been attempted in New York has been 

 successfully carried out in Germany, and a more 

 careful copying of the details and methods of 

 Messrs. Siemens & Halske would have pro- 

 duced success. The enormous traffic on these 

 roads taxes to the utmost the carrying-capacity 

 of the steam-plant, which is the result of half 

 a century of study and modification of machinery 

 of locomotives and cars. The substitution of 

 electric motors for steam-locomotives will be a 

 gradual process, and will progress just in pro- 

 portion to the engineering skill brought to bear 

 upon the problem. W. D. Marks. 



CARTWRIGHT LECTURES ON 

 PHYSIOLOGY. 



While physiological science has made rapid 

 advances in recent years, there are still many 

 problems which it has as yet failed to solve, not- 

 withstanding the fact that many patient and 

 skilled investigators have devoted their entire 

 time and energy to their solution. Among these 

 problems, none is of greater interest and impor- 

 tance than the life-history of the blood, and to its 

 elucidation the best minds in Europe and in 

 this country have been directed. Prof. William 

 Osier, M.D., of the University of Pennsylvania, 

 was invited to deliver the fifth course of the Cart- 

 wright lectures of the Alumni association of the 

 College of physicians and surgeons of New York, 

 and selected as his subject, * Certain problems in 

 the physiology of the blood.' The course of these 

 lectures began the evening of March 23, at the 

 hall of the Young men's Christian association. 



The first lecture dealt with the blood-plaque, 

 which is also known as the elementary corpuscle 

 of Zimmerman, the haematoblast of Hayem, the 

 third corpuscle and blood-plate of Bizzozero. In 

 blood withdrawn from the vessels, in addition to 

 the red and white corpuscles, are seen grayish 

 granular masses, being from ten to fifteen times 

 the size of a red corpuscle. These are known as 

 Schultze's granule masses. They are made up 

 of small bodies, which are of uniform size, and, 

 seen in face, have a disk shape, and in profile ap- 

 pear as rods. These bodies are the blood-plaques. 

 Their diameter is from 1.6 micro-millimetres to 3.5 

 micro-millimetres. They are always found in mam- 

 malian blood, though their number is subject to 

 considerable variation, in health averaging one 



to twenty red corpuscles. The estimates of their 

 number, made with the haemacytometer, give 

 about two hundred and fifty thousand of them to 

 each cubic millimetre of adult blood. In the 

 new-born this may be doubled, as also in con- 

 sumption. In fact, in all wasting diseases their 

 number is much increased, as not only in con- 

 sumption, but also in cancer and in anaemia ; and 

 they appear sometimes to occupy nearly the whole 

 field of the microscope. During acute fevers they 

 are much diminished in number, and again in- 

 crease during convalescence. 



When the blood is withdrawn from the blood- 

 vessels, these plaques have a tendency to conglu- 

 tinate, forming the granule masses of Schultze ; 

 and so rapidly does this occur, that it would ap- 

 pear to be the condition in which they exist while 

 within the vessels. This is, however, not the case, 

 but is a property which they possess analogous 

 to the nummulation of the red corpuscles. That 

 this state of conglutination is not the natural one 

 may be shown by examining the blood while 

 circulating in a living animal, as in the omentum 

 of a guinea-pig or rabbit, or in the subcutaneous 

 tissues of a new-born rat, which is admirably 

 adapted to the purpose. Or, if a drop of a solu- 

 tion of osmic acid (one per cent) or Pacim's fluid 

 be placed upon the tip of the finger, and then the 

 finger pricked, so that a drop of blood will flow 

 directly into this solution, and then the whole 

 transferred to a microscope-slide and examined, it 

 will be found that the plaques are isolated, and 

 the tendency to coherence has been overcome. 



There are some investigators who hold to the 

 opinion that these blood-plaques are disintegrated 

 white corpuscles, but the objections to this ex- 

 planation are numerous and incontrovertible. It 

 may therefore be considered as established that 

 the blood-plaque is a separate entity, and distinct 

 from the mature red and white corpuscle. 



The history of these corpuscles may be divided 

 into three periods. In the first, prior to 1877-78, 

 a number of investigators were at work upon it, 

 among them Donne, Zimmerman, and Erb. In 

 1874 Osier pointed out that the granule masses of 

 Schultze only formed after the blood was with- 

 drawn from the blood-vessels. In the second 

 period, 1877-78, Hayem demonstrated the exist- 

 ence of this third corpuscle, and called it haemato- 

 blast. In 1882 additional researches were made 

 by Bizzozero, who described it as a blood-plate. 

 In the third period, from 1882 to the present time, 

 a number of investigators have been at work, and 

 I here have appeared some twenty different articles 

 upon the subject. Kemp has been investigating 

 the question at the Johns Hopkins university, and 

 his paper will contain a full bibliography. 



