IOO E. G. SPAULDING. 



fertilization ; l or the spermatozoon may carry enzymes." " Either 

 of these two causes affects the most important qualities of life 

 phenomena, /. c., causes the proteids (i) to change their state, or 

 (2) to take up or lose water." 2 Further details as to these two 

 possible events are not given, however, but it is quite evident that 

 the two may be coincident, so that the latter change may take 

 place in any case. 



To summarize systematically, a cell division can be caused 

 in various forms by one or more of the following classes of stim- 

 uli : (a) mechanical ; (//>) heat (or cold); (c) osmotic ; (V) chem- 

 ical, or, if one will, ionic ; the third for the reason that either of 

 the electrolytes MgCl, or NaCl, or the non-electrolyte sugar, 

 maybe used ior Arbacia ;* therefore no specific chemical effect is 

 to be accepted here. The fourth, a distinctly chemical effect, is 

 evident, for HC1 is effective for Asterias eggs and KC1 is not ; 

 so also only the Ca ion for Amphitritus. Here then it is the 

 kation that is considered to cause the segmentation, but that a 

 fundamental chemical effect different to an ionic, i. c., electrical 



/ 



charge effect is present is shown by the fact that, keeping the 

 osmotic pressure and the number of charges on the kation the 

 same, but changing the ions, the effect is different. This is con- 

 firmed by the comparison of the action of KC1 and NaCl on 

 muscle. 4 A specific chemical effect is therefore not done away 

 with even if the difference in effect is reduced to a difference in 

 the path of the charge moving around the atom. For the cause 

 of this latter difference must in turn be a fundamental difference 

 in the atoms themselves. The same kind of proof of an irredu- 

 cible and ultimate chemical difference is found in the results of 

 Lillie's work on the effect of Na, K, Ca and Mg salts on Aren- 

 icola and Polygordius, and of Mat hews on the different stimu- 

 lating effects on the nerve of NaCl, NaBr, Nal and NaFl. This 

 fundamental chemical difference is related to the difference in so- 

 lution tension, as Mathew's work this past summer has shown. 

 However, not alone the stimuli, the external agents initiating 



, J. , Am. Jour, of Physiology, III., III. 

 2 Loeb, J., Am. Jour, of Physiology, III., IX. 

 3Loeb, Am. Jour, of Physiology, IV., IV. and III., IX. 

 4 Loeb, Am. Jour, of Physiology, III., VIII. 



