RECORDS OF MEETINGS 271 



their way home. There may be readily a combination of the two methods 

 in special cases. 



In the second part of the paper it was shown that a very large per- 

 centage of people, amounting to the order of 50 per cent, are accustomed 

 to think of far distant places in an entirely different direction than they 

 really are, amounting to from 45° to 180° from the real direction. The 

 subjects tested knew the correct direction within a few degrees. Statis- 

 tics seem to indicate that individuals having these "imaginary maps'^ 

 were more apt to be confused with respect to direction than those not 

 having them. 



Dr. Trowbridge's second paper also consisted of two parts, ^and in 

 the first the author showed that birds in a large flock when migrating, in 

 all probability, average their errors with respect to a certain distant des- 

 tination, and if this is the case the explanation of the migration in large 

 flocks of many species of birds can be explained, also ; the principle would 

 prevent single birds from going astray. 



The second part of the paper related to the echelon formation of 

 flight of many large birds when flying in flocks; the explanation given 

 being that it is the most protective arrangement. Evidence was brought 

 forward to show that in this formation the birds in the flock can see for- 

 ward as well as to the side, these regions are the chief "danger zones" 

 that the flying flock is subjected to. The paper was illustrated by dia- 

 grams, and by photographs of blue geese taken by Mr. Herbert K. Job 

 at Marsh Island, on the Mississippi delta. 



Dr. Wells said in abstract: One subject was highly practised in the 

 tapping test 51^ years ago. Six other subjects were highly practised in 

 addition and number-checking tests nearly 3 years ago. The present ex- 

 periments were made to ascertain the amount and character of the loss 

 during the relative disuse of the functions. In all tests the loss found 

 was about half the percentile amount gained by practice. The renewal 

 of practice does not bring with it an especially rapid practice gain. Per- 

 sons who gain much in the addition test regularly tend to lose much in 

 it, but this is not true in the number-checking test. Persons who lose 

 much in the one test, however, tend also to lose much in the other, 

 although the amounts of practice gain in them are negatively related. 



Dr. Lyon said in abstract : The various conceptions of the terms hallu- 

 cination and illusion were taken up in detail and it was shown that, al- 

 though no sharp line of demarcation could be drawn between the two 

 terms, yet the distinction was sufficiently fine to warrant their separa- 

 tion in an experiment such as the one under consideration. An halluci- 

 nation was defined as a subjective sensory image arising without the aid 



