NOVEMBER 12, 1897. ] 
associate professor of mathematics at the Uni- 
versity of Krakau. 
DISCUSSION AND CORRESPONDENCE. 
HOW TO AVOID THE DANGERS OF FORMALIN. 
To THE EpiToROF SCIENCE: In the issue of 
ScrencE for October 22d I note a letter by Dr. 
Dall, of the United States National Museum, in 
which the use of formalin for the preservation of 
zoological objects for dissection is declared to 
be dangerous to the cuticle, to the digital neu- 
ral terminals and to the eyes of the dissector. 
When working with formalin my eyes and 
nasal passages have been affected and it seemed 
to me that its use might be fraught with some 
danger. But the effect of the gas arising from 
specimens and of the solutions has never given 
in my case such serious trouble as seems to 
have been given the person of whom Dr. Dall 
speaks. To be contrasted with the effects of 
the reagent in this case is the fact that formalin 
and formaldehyde have come to be regarded as 
very important germicidal disinfectants to be 
used in inhabited rooms, where, we are told by 
members of the medical profession to which Dr. 
Dall appeals, that their use need not endanger 
in any way the inhabitants. Special lamps are 
on the market for generating formaldehyde 
from wood alcohol, and to be used in just such 
rooms. There may also be noted an experiment 
performed upon a calf, in which the animal 
was exposed for five hours to an atmosphere 
containing about 2% of formaldehyde. The 
only noticeable effect was a slight cough and a 
slight watering of the eyes, both of which dis- 
appeared upon bringing the animal into fresh 
air. What might have happened had the ani- 
mal been subjected to such an exposure daily 
for several weeks is a question that remains to 
be solved. In view of the fact that formalin 
seems destined to be used to a very great ex- 
tent in laboratories and museums, and also in 
view of its haying been recommended as a dis- 
infectant to be used as noted above, experi- 
ments to determine how great an exposure 
eyes, cuticular organs and mucous membranes 
ean stand without injury can have nothing less 
than a very great importance. 
But even though the use of the reagent is as 
dangerous as the case of the slug dissector men- 
SCIENCE. 
rs 
737 
tioned by Dr. Dall would lead one to think, 
such dangers may be obviated by taking ad- 
vantage of the strong affinity formaldehyde 
and ammonia have for one another. In rooms 
where formaldehyde is used dishes of ammoni- 
ated water may be placed, and specimens pre- 
served in formalin may be washed in ammoni- 
ated water before dissection, with the result of 
completely neutralizing the effects of the dis- 
infectant or preservative. 
F. C. Kenyon. 
WASHINGTON, D. C. 
PROFESSOR CATTELL’S REVIEW OF ‘SIGHT.’ 
IT RARELY ever reply to any criticism of a work 
of mine. I never do so unless to explain some- 
thing misunderstood. But in the case of Pro- 
fessor Cattell’s review of ‘Sight’ in ScIENCE 
for September 24th, I feel the less hesitancy be- 
cause of his generous estimate of its value. 
There are three points on which I wish to ex- 
plain myself more fully. 
1. Professor Cattell objects to my view that 
“the central spot is necessary to the develop- 
ment of the higher faculties of the mind,’’ and 
asks in rejoinder: ‘‘ May not the mental facul- 
ties of the born-blind be developed >’? And well 
might he object if limplied anything so absurd. 
But he has entirely mistaken my meaning. 
Perhaps I am partly responsible for a possible 
ambiguity, and, therefore, thank him for 
drawing my attention to it. I did not mean 
development of the higher faculties in the ontog- 
eny, but in the phylogeny, of man; not in the 
education of the individual, but in the origin of 
the race. Perhaps, however, I ought to have 
used the word evolution instead of development. 
I shall make the correction. 
2. Again Professor Cattell objects to my 
saying: ‘‘ We see things double except under 
certain conditions.’? He says: ‘This is bad 
psychology. We learn to see them double.”’ 
Of course, we learn to consciously see them 
double. But if we see only what we con- 
sciously see, we see comparatively little. The 
phenomena of double vision lie so near the sur- 
face of consciousness that the least attention re- 
calls them. They may be called subconscious, 
but we base our judgments on them all the time. 
Surely it is the business of psychology to bring 
