1896.] MICROSCOPICAL JOURNAL 37 



the object or a skeleton of the picture which it is intended to 

 produce. By the aid of the micrometer screen of the micros- 

 cope, the appearance presented in the several strata of the spec- 

 imen ma}' be easily sketched in by an artist. A more com- 

 plete picture may be reproduced by the half-tone process, and 

 thus better results obtained than are possible by either drawing 

 or photography alone. — Modern Medicine. 



BIOLOGICAL NOTES. 



An Atlas of Nerve Cells, By M. Allen Starr, M. D., Ph.D., is 

 in press. It is the object of this atlas to present to students 

 and teachers of histology a series of photographs showing the 

 appearance of the cells which form the central nervous system, 

 as seen under the microscope. These photographs have been 

 made possible by the use of the method of staining invented by 

 Professor Camillo Golgi of Turin. This method has revealed 

 many facts hitherto unknown, and has given a conception of 

 the structure and connections of the nerve cells both novel and 

 important. In the light of these facts, it has been necessary to 

 discard many of the views previously taught by anatomists, 

 and to revise some of the physiological and pathological data 

 supposed to be fundamental. 



The nervous system is now known to be composed of a vast 

 number of independent units, called neurons, which consists of 

 a cell body with two varieties of branches, called dendrites and 

 neiiraxons. The cell bodies vary in size, shape, and appearance ; 

 their dendrites, formerly known as j^rotoplasmic processes, pre- 

 sent great differences in form, length, and manner of subdivis- 

 ion ; their neuraxons, formerly called axis cylinder processes, 

 and believed to have no branches, are now known to give off 

 many little collateral offshoots as important as the main trunk. 



The arrangements of these neurons varies greatly in different 

 parts of the nervous system. In the spinal cord they are col- 

 lected into groups arranged in a long cylindrical column. In 

 the cerebral axis they are scattered among the various nerve 

 tracts as well as collected into separate groups. In the basal 

 ganglia they are gathered into large masses separable into divis- 



