December 2, 1887.] 



SCIENCE. 



275 



on whether it appeals strongly and for some time to the senses, 

 especially of sight. 



I know, from personal experience and observation, that it is not 

 uncommon for man to temporarily lose the power of the senses 

 under excitement, while the body still performs its normal functions 

 intelligently. Perhaps this would explain the third case men- 

 tioned by iVIr. Hall. The gentleman remembered the runaway, but 

 became so excited in checking the horse that his senses were 

 oblivious to all surroundings. 



In my own case the cause evidently acted before my eyes, and I 

 have been led to believe that the cause of an injury may act so sud- 

 denly as to produce unconsciousness before the impression made 

 on the senses can reach the brain. 



Another case was unconsciousness produced by poisoning with 

 sulphuretted hydrogen. I went into the attic to regulate a gener- 

 ator, and shut the trap-door, as I had to pass over it to reach the 

 generator. There was but one window in the room. It was down, 

 and about fifteen feet away. There being no gas at the hoods in 

 the laboratory led me to think the iron sulphide was out. I dis- 

 connected the tubing, and found high pressure, which forced several 

 gallons of gas into my face. It produced involuntary respiration, 

 and my lungs were drawn full. Deeply impressed that my only 

 hope of life was fresh air, I started for the window at once. Al- 

 most instantly I began to get dizzy, and my vision was strongly 

 impaired. The window, only a few feet away, seemed very re- 

 mote, and no larger than my hand. My rapid advance toward it 

 gave me the strange impression that my legs were half a mile long. 

 I became unconscious before reaching the window, and all is a 

 blank until I found myself rushing down the stairs, two stories be- 

 low, still impressed with the necessity of reaching pure air. In an 

 unconscious state, I raised the window about eight inches, raised 

 the trap-door, and fell headlong down the stairs to the laboratory, 

 and was found by one of the students deathly pale, the blood set- 

 tled under my eyes, my muscles rigid, and large drops of cold per- 

 spiration on my face. Soon after the student reached me, I began 

 to show signs of recovery, and suddenly sprang to my feet, exclaim- 

 ing, "I must have air!" and rushed down the stairs, regaining 

 consciousness on the way. 



This case shows suspension of a train of thought which was 

 taken up where it was left off, and pursued after a season of uncon- 

 sciousness. It also shows several intelligent trains of thought 

 pursued in the absence of general consciousness, leaving no im- 

 pression on the memory. I have often asked myself what directed 

 me to raise the window and the trap-door, and have wondered 

 whether there are centres in the brain to direct intelligent action 

 for self-preservation in the absence of consciousness. 



My intention was to open the window for air, but I have no 

 knowledge of having done it. This has led me to ask whether im- 

 pressions made on the brain during consciousness may not be au- 

 tomatically executed after the avenues to the external world are 

 closed. May not a state of partial unconsciousness, as in som- 

 nambulistic sleep, be produced by injury, and well-directed trains 

 of thought be executed and leave no impression on the memory? 



A friend of mine has a blank of three weeks in her life while sick 

 with typhoid-fever, yet was unconscious only the last ten days of 

 the time. I have always explained such cases on the basis that 

 bodily condition has much to do with the indelibleness of impres- . 

 sions made on the brain. When the body is weak, the impressions 

 are weak and forgotten. Even in a state of health there are many 

 perceptions that make no lasting impression. F. L. Harvey. 



Maine State College, Orono, Me., Nov. 22. 



American Microscopes. — A Complaint. 



Every autumn when the colleges and medical schools of the 

 country begin their academic years, there are many students who 

 come to their instructors seeking advice in regard to the purchase 

 of microscopes. Often they appear already furnished with an in- 

 strument of which they are anxious to learn that the lenses are 

 particularly good. 



As it has been my duty for several years to conduct a large class 

 in practical histology, I have had frequent applications for advice 

 about microscopes, and have seen and examined a great many dif- 

 ferent stands, and the lenses of many manufacturers. I have had 



therefore, opportunities to test the practical convenience and ad- 

 vantages of the many sorts of microscopes which the students have 

 brought along with them. The result of this experience is the con- 

 viction that it is undesirable to recommend a student to purchase 

 any microscope whatsoever of American manufacture, and to. 

 always counsel him to obtain, if possible, one of the German or 

 French instruments. 



In order to make my judgment more clear, I may add that I 

 know of no American microscope which I should like to purchase 

 at any price, for my own use in histological or embryological work. 



I venture to express this adverse opinion in regard to Americaa 

 microscopes in the hope of inducing some of our opticians to man- 

 ufacture a stand for a microscope suitable for the use of students 

 of histology and biology. It appears to me that the simple model 

 now almost universally adopted in Europe is far superior to every 

 thing offered us in rivalry to them by our own dealers. 



To justify myself, I should like to give, first, the reasons for my 

 disapproval of the American forms ; and, second, the reasons for 

 my preference of German forms. The fundamental error in micro- 

 scopes of American manufacture is that they are for the most part 

 constructed with a view of, I might almost say, entrapping inexpe- 

 rienced purchasers. The zeal of the maker is turned too much to. 

 decorative lacquering and nickel-plating : he adds to his stands as. 

 great a variety of mechanical contrivances and adjustments as the 

 price of the stand will permit, and many of these contrivances are 

 not really commendable for their utility. In the majority of cases, 

 the stands are made to tilt, which, for one that uses the microscope 

 for real work, is an almost useless luxury, because he who really 

 works in histology necessarily examines fresh specimens in fluids,, 

 or at least constantly has on the stage of "his microscope prepara- 

 tions in various stages of unreadiness, and not mounted in a perma- 

 nent form. All this implies the constant use of fluids, and, if the 

 stage of the microscope is inclined, the use of liquids is impracti- 

 cable. Any one, therefore, who uses his microscope for the ordi- 

 nary purposes of a student or an investigator, or in connection with 

 clinical or pathological work, very soon falls out of the habit of 

 tilting his microscope. Hence it is, that, while making a micro- 

 scope to tilt renders it considerably more expensive, it adds nothing 

 essential to the convenience of the stand for laboratory work. This 

 same fact, that most of the work must be done with the tube of the 

 microscope vertical, renders it indispensable that the microscope 

 should not be too high ; so that we must put down the ten-inch 

 tube as a bad feature for a student's microscope. A rack and 

 pinion is undoubtedly advantageous : it renders the use of the 

 microscope more convenient, and increases its durability by dimin- 

 ishing the strain upon the stand during the coarse adjustment of 

 the focus. When this adjustment is effected by shoving the tube 

 with the hand, the microscope wears out sooner than with the rack- 

 and-pinion movement ; yet even the rack and pinion, which are so 

 generally put on our American microscopes, are not indispensable,, 

 and the greater part of the histological and embryological investiga- 

 tions of the past twenty years have been made without the employ- 

 ment of this convenience. 



The stage of the American microscope is very faulty. The large 

 movable glass plate with a hole through it is a toy fit only for an 

 amateur or fancy collector : it interferes with the use of fluids, and 

 with the freedom of movement of the slide over the field of the 

 microscope, — the two things which are most indispensable in 

 practice. A good stage should be large and flat, with nothing upon 

 it except a pair of spring clips and a hole for a diaphragm. The 

 diaphragms are often a matter of particularly fanciful construction. 

 Thus the Iris diaphragm is often introduced to allure the inexperi- 

 enced, but it is not a good form except in conjunction with an 

 acromatic condenser. There are other details of construction 

 which are equally open to unfavorable criticism, but it is unneces- 

 sary to go into their discussi on. 



Unfortunately, while we see so much pains expended upon the 

 brass-work of the microscope, we see a neglect of the optical mem- 

 bers of the instrument ; so that the microscope as a whole is con- 

 verted into a showy piece of apparatus, and the eye-pieces and ob- 

 jectives are generally, though not always, of a decidedly inferior 

 character: when they are really good, the lenses are very expensive. 



If, npw, our manufacturers would reverse the distribution of their 



