138 LECTURES ON IMMUNITY 



Similar observations may be made regarding the growth 

 of eggs of animals after their fertilisation, as observed by 

 Hertwig and Karl Peter. 1 The development of these eggs 

 was followed by means of observations of the cell-division 

 which went on much more rapidly at higher than at lower 

 temperatures. Even chemical influences, especially a 

 small addition of hydroxyl-ions to the sea water, are often 

 very remarkable. The eggs of Arbacia develop a little 

 more rapidly in sea water containing 2 c.c. of o. I n. alkali 

 in 100 c.c. of water than if no alkali has been added. An 

 equivalent amount of HC1 retards the development. 2 The 

 increase (/) for increase of the temperature 10 C. and the 

 corresponding value of ft are given below. They are 

 valid for a mean temperature of about 16 C. : 



Eggs of Echinus microtuberculatus First stage /= 2. 29 yu, = 1 3,700 



Later stages 2.03 11,700 



Eggs of Sphtxr echinus granularis First stage 2.30 13,800 



Later stages 2.08 12,100 



Eggs of Ranafusca (Hertwig) First stage 2.23 13,300 



Later stages 3.34 20,000 



As we see, ^ is of quite the same order of magnitude as 

 that for the production or assimilation of carbonic acid by 

 green plants. Further, at low temperatures (3-5 C.) the 

 />& for the eggs of the frog has a very high value about 

 ten times those given above ; and at the temperatures of 

 over 37 C. the life process is hindered by increase of tem- 

 perature. In a similar manner behaves the heart-beat of 



1 Hertwig: Archiv f. mikrosk. Anatomic, 51. 319 (1898); Karl Peter: 

 Archiv f. Entwicklungsmechanik, 20. 130 (1905). 



2 J. Loeb: Archiv / Entwicklungsmechanik, 7. 631 (1898). Cf. above, 

 the influence of alkalies and acids on the velocity of destruction of lysins. 



