354 THE POPULAR SCIENCE MONTHLY. 



again after the thirtieth year of age. Mr. Tait believes that the 

 hollow is associated with the embryonal process connected with 

 the neural canal and its closure. He referred to the tailless cats 

 of the Isle of Man, and tailless guinea-pigs which, like man, pos- 

 sess only an os coccygis with three pronged centra infolded in 

 the skin ; and thought that he might conclude from certain in- 

 dications that some of these animals, and perhaps also the pre- 

 decessors of man, may have lost the tail in consequence of a 

 malformation, probably in man through the not rarely appearing 

 spina bifida. We well know how such malformations tend to 

 become hereditary ; and the sacral dimple might be called the scar 

 of the lost tail. The hereditability of such malformations is well 

 marked. When Dr. Wilson crossed a Manx tomcat with a com- 

 mon cat, seventeen out of twenty-three kittens were tailless ; but 

 when female cats of the Isle of Man were crossed with common 

 tomcats all the kittens had tails, though somewhat shortened. 

 Prof. Ecker has suggested a less fanciful explanation of the origin 

 of the sacral dimple. He supposes that the later inward curving 

 of the tip of the much straighter coccyx in the foetus— which is 

 connected with the skin by the caudal ligament— draws the cor- 

 responding spot on the skin into a funnel shape of greater or less 

 depth. On the other hand, Ecker would rather regard the glabella 

 coccygea as the lower fontanel, or later point of closure of the 

 sacral canal. 



The embryonal processes and normal conditions of formation 

 thus briefly sketched are sufficient in general to permit most of 

 the cases of so-called tail-formations in men, which occur with 

 tolerable frequency, to be recognized as easily explainable irreg- 

 ularities of natural growth. The case deviating least from the 

 normal condition concerns only the skin-covering, and exhibits 

 itself in an excessive hairiness of the sacral and coccygeal region 

 (frichosis sacralis). We have seen above that this spot in the em- 

 bryo reo-ularly bears a hair-twirl, which is not rarely prolonged 

 into a hairy pencil or taillet. We can hardly consider it an im- 

 portant variation if this hairy taillet is exceptionally not absorbed, 

 but endures and grows stronger after birth. In the so-called hairy 

 men we evidently have persons in whom, according to all appear- 

 ance, the wool-hair of the foetus has grown to a far greater extent, 

 or at least possesses the same properties of alignment and direc- 

 tion. The chief physician of the Greek army, Dr. Bernhard Orn- 

 stein, having observed several cases of extraordinarily abundant 

 hairiness in the sacral region among Grecian recruits, has given 

 continued attention to this phenomenon, and has determined some 

 very remarkable cases of it. The most striking of these cases was 

 that of the twenty-eight-year-old recruit Demeter Karus, of the 

 eparchy of Corinth. The whole sacral region appears to be cov- 



