94 PEARL BRIGGS BULLARD 



The ape and monkeys, as expected from their high position 

 among mammals, show a relatively large dorsal funiculus. The 

 spider monkey, for example, has an average ratio for the three 

 regions of 2.39, that is to say, the dorsal funiculus of the spider 

 monkey is only slightly less than one-half the size of the ventro- 

 lateral. The relatively large dorsal funiculus of this animal is 

 explained in part at least by the fact that it possesses an excep- 

 tionally long, large and specially functioning tail whose skin 

 area must require a large additional number of ascending axones 

 in the cord. The striking motility and functional control of 

 this tail must mean additional and no doubt a special bundle of 

 pyramidal axones. These latter, descending in the lateral funicu- 

 lus, render the dorsal funiculus only relatively less large than it 

 would be otherwise. 



I am not able to explain why the cord of the raccoon should 

 show such a relatively large dorsal funiculus which, in the cervi- 

 cal region is to the ventro-lateral funiculus as 1 is to 2.13, being 

 relatively larger in this region than that found in any of the 

 other animals. The upper extremities of the raccoon are some- 

 what less highly functional than those of the monkey, its tail is 

 relatively no larger and but little more functional than that of 

 the dog or fox and its pjTamidal tract does not appear to course 

 in its dorsal funiculus. The mouse and agouti have relatively 

 large dorsal funiculi, due, at least in part, to the fact that they 

 have the crossed pyramidal tract in this funiculus. 



Column 4, table 8b, gives the fox as having an average dorsal 

 funiculus less than one-fifth the size of the ventro-lateral. This 

 must mean that he possesses an enormous number of association 

 fibers in the lateral funiculus or that the spino-cerebellar fasciculi 

 are unusually large. It is to be noted that the great variation 

 in relative size of the two funiculi which most of the animals 

 show throughout the three regions is not evident in the fox (table 

 8b). The acuteness of the fox in reflex action is proverbial and 

 complex reflex activities are anatomically explained on the basis 

 of abundant association fibers (fasciculi proprii). Also, for cere- 

 bral muscular control, this animal may have relatively large 

 pyramidal fasciculi. The sheep and rabbit likewise are popu- 



