EFFECT OF ACTIVITY ON NER-VT. CELLS 351 



Representatives of practically all these types of cells were 

 found in my specimens, from the resting control animal, as well 

 as from those animals exercised for one, two and a half, and 

 five hours. In order to determine as accurately as possible the 

 relative proportion of these t\'pes of cells in the different speci- 

 mens, a table was made out listing each of these cell tj-pes, and 

 then beginning with a section under the microscope, every cell 

 showing a complete nuclear membrane was taken in order, and 

 checked in the proper colunm. In this way over three thousand 

 cells were counted with the result listed in table 3. 



As wall be seen in the table, the number of a particular type 

 of cell varies considerably, but this variation is the same for the 

 different animals. There are neither progressive clianges in the 

 juorphology of the cells from rest to exliaustion nor are there 

 any qualitative or quantitative differences in t>'pe of cells from 

 resting and fatigued or even exhausted animals. The animals 

 used in Dolley's experiment exercised at most up to three to four 

 hours altogether. Dolley also describes these t^TDes of cells as 

 persisting in the effort to recu])erate for from two weeks to several 

 months after exercise no more severe than tliat of two or three 

 hours running in a treadmill. All these types of cells are ad- 

 mittedly present at the same time (Dolley, .American Journal of 

 Physiology, vol. 28, p. 151). Dolley describes thirteen stages 

 of fatigue in one aniniid where the animal exercised one hour in 

 a tread mill. Also, the cells selected by him for illustration of 

 these stages are taken from a single preparation of three sec- 

 tions in the same experiment. Obviously the observations were 

 not over a large enough range of sections nor sufficiently con- 

 trolled by actual counts of the various tj-pes of cells. In the 

 Journal of Medical Research, vol. 21, p. 104, Dolley says, 

 "Measurements were made of five cells of each type in five 

 anaemia exjieriments, one a fatal resuscitation, the other a re- 

 peated hemoj-rhage ;" a little farther on, ""^Measurements were 

 made of ten cells in each of three groups." A great many cells 

 were skipped (those not entire) in Dolley's method of counting, 

 giving a large leeway for a personal factor in the selection of 

 types. Ibid, volume 20, page 291, " ^Measurements were made 



