CHANGES OF FOEM IN CELLS. 19 



of human blood are capable of effecting a considerable amount 

 of locomotion at a temperature of from 100 Fahr. to 104 Fahr. 

 It is well known how great is the influence of particular tem- 

 peratures on the development of the egg, and even if the 

 movement of the cells is not the chief factor in this process, it 

 certainly plays a very important part in it. We may readily 

 conceive that an analogous influence must be exerted by any 

 increase of temperature occurring in pathological processes. 



A peculiar effect of temperature is described by Kuhne,* as 

 observable in the fresh-water amoeba, which at 95 Fahr. as- 

 sumes a spherical form. 



Lastly, Peremeschkof states that the large cells at the bottom 

 of the yolk cavity in the eggs of fowls, contract and dilate at a 

 temperature of from 89*3 Fahr. to 93 Fahr. 



b. MECHANICAL INFLUENCES. Kuhne was the first to com- 

 ment on the effects of indirect mechanical irritation, stating 

 that after he had stimulated the margin of the cornea in a frog, 

 he saw stellate corpuscles become fusiform. 



Ij have made a few experiments on the effects of direct me- 

 chanical irritation, and have observed that when blood diluted 

 with a solution of common salt, containing one half per cent., 

 is placed under a cover, and this last, by the withdrawal of the 

 fluid, is allowed to sink to such an extent that the white cor- 

 puscles are flattened out, they alter their shape with consider- 

 able vivacity, especially if they are allowed to remain in this 

 position for some time. If now a drop of fluid is brought to 

 the margin of the cover, this will again be raised from the slide 

 in proportion to the quantity added. The flat corpuscles may 

 now be observed to contract into small angular lumps, and after 

 a short time to change from this into a moderately expanded 

 form. 



The compressed corpuscles here behave like the muscles of insects 

 under the compressorium, which continue their movements for a time, 



* Protoplasma, 1864. 



t Wiener Sitzungsberichte, 1868. 



J Wiener Sitzungsherichte, 1867. 



