550 THE POSTERIOR PITUITARY AND THE NERVOUS SYSTEM. 



diminution of the gemmulae wherever the swellings are found" 

 which suggests that these minute ball-tipped projections from 

 all collaterals are structurally similar to them, and that, when 

 the engorgement exceeds in centrifugal pressure the resistance 

 of a given area, the walls of the latter, including the gemmules, 

 are more or less flattened out. Suggestive, likewise, is the fact 

 that all the gemmules stand out boldly in both preparations. 

 As many as thirty-six or forty-eight hours having elapsed be- 

 fore death ensued, the animals were evidently submitted to a 

 primary period of intense stimulation, during which the gem- 

 mules were overdistended to such an extent as to cause them 

 to lose their retractile property. Indeed, the sudden cessation 

 of adrenal functions and consequent death must have left the 

 cerebral structures much as if the animals had been suddenly 

 killed. 



Of marked interest in Fig. 3 is the presence at the ex- 

 tremity of the main, or apical, dendrite of a section of what 

 appears to us to represent a fiber or capillary from which the 

 neuron with which it is connected might have derived its blood- 

 supply. The fact that it crosses its path suggests that the den- 

 drite itself may be a branch of the vessel. Berkley describes 

 this neuron as follows: "Projection-cell of the long apical 

 process variety, showing numbers of large swellings of the pro- 

 toplasm of the apical dendrite, thinning of the protoplasm of 

 the stems in the interval between the nodules, and considerable 

 loss of the gemmulse along the margins. The lateral branches 

 have mainly disappeared. The basal processes are retained 

 intact." 



The nodules seem to us to also illustrate the process 

 through which the collateral fibers become detached from the 

 main stem, as shown by the denuded cells represented by Figs. 

 4 and 5. The thinning of the plasma between the stems would 

 account for the manner in which the lateral branches are de- 

 tached, viz.: when the apical dendrite becomes sufficiently 

 engorged the plasma ceases to circulate in one or more of the 

 nodules, and the intervening protoplasm, failing to be nour- 

 ished, disintegrates. That the basal processes should be the 

 last to yield in this cell (corresponding in this with the condi- 

 tion of the same stems in Figs. 1 and 2) seems but normal 



