LOEW AS A LIPTEROLOGIST 
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Chloropidae. Whether Schiner is always right I am incompetent to 
decide, but what induced me to refer to the question of recog¬ 
nizing descriptions is the experience I have had of Loew's method 
in that matter. 
For the purpose of recognizing an insect in one or more descrip¬ 
tions, two different methods may be used, one of which may be 
called the method of comparison, and the other the method of 
visualization. 
The method of comparison is the ordinary one, when the specimen 
to be determined is held up and compared in every detail with the 
description. In using this method, one is often bewildered by dis¬ 
crepancies, especially when the description is long. 
The method of visualization consists in examining the specimen 
first, and impressing its principal features upon one’s memory, so 
as to be capable of visualizing it in its absence. The next step is 
to read the description (or descriptions, when there are several), 
and, while doing it, to build up the described insect in one’s imagi¬ 
nation. Thus a mental image is produced in which the visualized 
species to be determined can easily be recognized, even in the 
absence of the specimen. After having thus selected a description 
apparently answering the specimen to be determined, the descrip¬ 
tion is read for a second time with the specimen in hand; and this 
second reading enables one to decide whether the discrepancies 
are important or not, and, in the latter case, to accept the 
identification. 
The method of visualization is quicker and surer than the other, 
and, with it, I have often succeeded in deciphering Walker’s some¬ 
times long but unmeaning descriptions. In the following instance 
the advantage of the method of visualization was unmistakably 
proved. Loew had prepared a preliminary list of American Dasypo- 
gonina , in which the species known to him were distributed among 
his new genera. Some of Walker’s and other unrecognizable specific 
descriptions were enumerated under the heading Dasypogon in the 
widest sense. Loew challenged what he called my perspicacity 
(“Ihren Scharfsinn”) in unravelling some of Walker’s species of 
the latter group. I find my identifications (which Loew accepted) 
enumerated in a letter of mine of October 9, 1874, of which I re- 
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