264 DR. HUBERT AIRY ON A DISTINCT FORM OF TRANSIENT HEMIOPSIA. 
Regarded merely as a disease, Teichopsia, though by no means unimportant, may be 
thought hardly deserving of the attention of scientific men ; but regarded as a veritable 
‘ Photograph ’ of a morbid process going on in the brain, its interest and importance 
cannot be too strongly insisted upon. 
In conclusion, I regret to be obliged to leave so much doubt upon so many points of 
the subject I have been dealing with. As more evidence arises, and more systematic 
observations are gathered, I hope these doubts may be removed. Meanwhile our duty 
is to collect and record fads, in confidence that they will arrange themselves into a theory 
sooner or later. No two cases of this disease present exactly the same features; every 
one is an illustration of the rest ; and by the accumulation and comparison of accurate 
records we may hope that the transition from facts isolated to facts linked by the clue 
of theory will be soon attained. 
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Explanation of Plates. 
PLATE XXV. 
Figs. 1-4. Early stages of sinistral Teichopsia (see p. 256) beginning close to the sight- 
point, as seen in the dark. The letter O marks the sight-point in every 
figure. 
Figs. 5-8. A similar series of the early stages of sinistral Teichopsia beginning a few 
degrees below and to the left of the sight-point. 
Fig. 9. Sinistral Teichopsia fully developed. 1. Beginning of a secondary attack, which 
never attains full development unless it arise on the opposite side. 
PLATE XXVI. 
Fig. 1. Diagram to show the progress of the attack in any given case of sinistral 
Teichopsia beginning close to the sight-point but a little to the left. The 
successive curves denote the successive stages of the attack and positions of 
the arch, not transgressing the median vertical line. 
Fig. 2. Similar to fig. 1, for a case of sinistral Teichopsia beginning some distance below 
and to the left of the sight-point. 
Fig. 3. Teichopsia, fading prematurely, losing continuity opposite the natural gap in 
its wall, and terminating by resolution. 
