THE PHYSIOLOGY OP THE NEURON. 525 



conveys but little exact information. And still, even this sus- 

 tains a deduction opposite to theirs. Indeed, the short period 

 of time that elapsed between the injection of the toxics in the 

 animals killed in this manner represented by 108 blocks of 

 slides must have sufficed to initiate retraction of the gem- 

 mules and the formation of varicosities, since only 10.2 per 

 cent, of these blocks show no varicosities. When, on the other 

 hand, the proportion of animals killed instantly by instru- 

 mental procedures 93 blocks of slides is analyzed, over two 

 and a half times as many, i.e., 28 per cent., are found to show 

 no varicosities. 



But a fair question suggests itself in this connection: 

 Why do the remaining 72 per cent, show any varicosities? 

 Only 14 per cent, of the blocks from the instantly killed ani- 

 mals are recorded as "varicose," the remaining 58 per cent, 

 being entered as "slightly" or "very slightly" varicose. In their 

 explanation of the scope given these terms, the first means "at 

 least some varicosities" and the second as "only very few vari- 

 cosities." Now, the authors state that "in the first nine cases 

 here recorded the brains were placed in fixing fluids within 

 three to five minutes." Nothing is said of the rest; so that 

 we may infer that the ten other brains were immersed after 

 longer intervals. We have previously seen, when the conver- 

 sion of myosinogen into myosin was studied, that oxidation 

 processes continued even after death: i.e., until all the oxygen 

 had been utilized. That this must be the case with the brain, 

 which contains one-fifth of the blood of the whole body, and 

 that products of metabolism, especially C0 2 , should form in 

 the entire encephalon is evident. It normally follows that we 

 have in this factor a potent cause for the retraction of gem- 

 mules and the formation of varicosities. 



Indeed, the contrast between the results reached speaks 

 for itself when compared to those of Goddard, who resorted 

 to procedures in which the exact condition at the instant of 

 death were preserved, "the parts of the head falling instantly 

 into large culture dishes warmed to 39 C." Even continua- 

 tion of the normal brain temperature was insured. And what 

 were Goddard's results? "It was difficult to find a single vari- 

 cosity on the dendrites of the morning puppy," i.e., the thor- 



