388 



PROF. TH. W. ENGELMANN. 



Naked masses of protoplasm of microscopic size, such as 

 Amoebse, colourless blood-corpuscles, wheu gradually warmed 

 up to the maximum, become spherical. Protoplasmic threads 

 of Uhizopods, vegetable cells, &c., generally become at first 

 varicose, and finally withdrawn into the main mass of the pro- 

 toplasm. Fig. 3 shows the difi'erent shapes assumed by a 



fiG. 3. — A colourless blood-corpuscle of a frog under the influence of 

 {a — m) a gradually increasing temperature, which («— jo) subsequently 

 diminishes. 



colourless blood-corpuscle of a frog, under the influence of 

 gradually warming and subsequent cooling, at intervals of five 

 minutes. 



From a to c the temperature was 12° C, the shape is only 

 slightly changed. At c the microscope, with the preparation 

 in a moist chamber, was placed in a Sach's warm box filled 

 with water at 50° C. After a few minutes the movements had 

 become visibly more active, and the cell crept forwards with, 

 up to I, an ever-increasing rapidity. At m it commenced, and 

 at n had completely entered into heat-rigor. The preparation 



